# 步驟 5：發布和訂閱影片
您可以使用下列方式發布到 IVS/訂閱 (即時) IVS：
+ 支援 WebRTC 和 RTMPS 的原生 [IVS 廣播 SDK](https://docs.aws.amazon.com//ivs/latest/LowLatencyUserGuide/getting-started-set-up-streaming.html#broadcast-sdk)。建議採用此方式，尤其在生產情境下更是如此。請參閱下列有關 [Web](getting-started-pub-sub-web.md)、[Android](getting-started-pub-sub-android.md) 和 [iOS](getting-started-pub-sub-ios.md) 的詳細資訊。
+ Amazon IVS 主控台：適用於測試串流。請參閱以下 。
+ 其他串流軟體和硬體編碼器：您可以使用任何支援 RTMP、RTMPS 或 WHIP 通訊協定的串流編碼器。如需詳細資訊，請參閱[串流擷取](rt-stream-ingest.md)。
## IVS 主控台
1. 開啟 [Amazon IVS 主控台](https://console.aws.amazon.com/ivs)。
(您也可以透過 [AWS 管理主控台](https://console.aws.amazon.com/)來存取 Amazon IVS 主控台。)
1. 在導覽窗格中，選取**舞台**。(如果導覽窗格已收起，選取漢堡圖示即可展開。)
1. 選取您要訂閱或向其進行發布的舞台，以前往其詳細資訊頁面。
1. 若要訂閱：如果舞台有一或多名發布者，您可以按下**訂閱**索引標籤下的**訂閱**按鈕來進行訂閱。(索引標籤位於**一般組態**區段下方)。
1. 若要發布：
1. 選取**發布**索引標籤。
1. 系統會提示您授予 IVS 主控台存取攝影機和麥克風的權限；請**允許**這些權限。
1. 在**發布**索引標籤的底部，使用下拉式方塊選取麥克風和攝影機的輸入裝置。
1. 若要開始發布，請選取**開始發布**。
1. 若要檢視已發布的內容，請返回**訂閱**索引標籤。
1. 若要停止發布，請前往**發布**索引標籤，並將按下底部的**停止發布**按鈕。
**注意**：訂閱和發布會耗用資源，而且連線到舞台的時間會產生每小時費用。若要進一步了解，請參閱 IVS 定價頁面上的[即時串流](https://aws.amazon.com/ivs/pricing/#Real-Time_Streaming)。
# 使用 IVS Web 廣播 SDK 發布和訂閱
Web
本節將引導您完成使用 Web 應用程式發布和訂閱階段的相關步驟。
## 建立 HTML 樣板
首先，建立 HTML 樣板並將程式庫匯入為指令碼標籤：
```
```
## 接受權杖輸入並新增加入/離開按鈕
在這裡用輸入控制填寫內文。這些做為輸入權杖，然後設定**加入**和**離開**按鈕。通常，應用程式會透過您的應用程式 API 請求權杖，但在本範例中，您將複製權杖並將其貼至權杖輸入。
```
IVS Real-Time Streaming
```
## 新增媒體容器元素
這些元素將為本機和遠端參與者保留媒體。新增了一個指令碼標籤，來載入 `app.js` 中定義的應用程式邏輯。
```
```
這樣就完成了 HTML 頁面，並且您應在瀏覽器中載入 `index.html` 時看到此頁面：
![\[在瀏覽器中檢視即時串流：HTML 設定完成。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/RT_Browser_View.png)
## 建立 app.js
繼續來定義 `app.js` 檔案的內容。首先，透過 SDK 的全域匯入所有必要的屬性：
```
const {
Stage,
LocalStageStream,
SubscribeType,
StageEvents,
ConnectionState,
StreamType
} = IVSBroadcastClient;
```
## 建立應用程式變數
建立變數來保留**加入**和**離開**按鈕 HTML 元素的參考，以及存放應用程式的狀態：
```
let joinButton = document.getElementById("join-button");
let leaveButton = document.getElementById("leave-button");
// Stage management
let stage;
let joining = false;
let connected = false;
let localCamera;
let localMic;
let cameraStageStream;
let micStageStream;
```
## 建立 joinStage 1：定義函數並驗證輸入
該 `joinStage` 函數採用輸入權杖，建立與階段的連線，並開始發布從 `getUserMedia` 中擷取的影片和音訊。
首先，定義函數並驗證狀態和權杖輸入。我們將在接下來的幾個部分完善此功能。
```
const joinStage = async () => {
if (connected || joining) {
return;
}
joining = true;
const token = document.getElementById("token").value;
if (!token) {
window.alert("Please enter a participant token");
joining = false;
return;
}
// Fill in with the next sections
};
```
## 建立 JoinSage 2：取得要發布的媒體
以下是將在階段上發布的媒體：
```
async function getCamera() {
// Use Max Width and Height
return navigator.mediaDevices.getUserMedia({
video: true,
audio: false
});
}
async function getMic() {
return navigator.mediaDevices.getUserMedia({
video: false,
audio: true
});
}
// Retrieve the User Media currently set on the page
localCamera = await getCamera();
localMic = await getMic();
// Create StageStreams for Audio and Video
cameraStageStream = new LocalStageStream(localCamera.getVideoTracks()[0]);
micStageStream = new LocalStageStream(localMic.getAudioTracks()[0]);
```
## 建立 JoinSage 3：定義階段策略並建立階段
此階段策略是 SDK 用於決定發布內容，以及要訂閱哪些參與者的決策邏輯核心。如需函數用途的詳細資訊，請參閱[策略](web-publish-subscribe.md#web-publish-subscribe-concepts-strategy)。
這項策略很簡單。加入階段後，發布剛剛擷取的串流，並訂閱每個遠端參與者的音訊和影片：
```
const strategy = {
stageStreamsToPublish() {
return [cameraStageStream, micStageStream];
},
shouldPublishParticipant() {
return true;
},
shouldSubscribeToParticipant() {
return SubscribeType.AUDIO_VIDEO;
}
};
stage = new Stage(token, strategy);
```
## 建立 JoinSage 4：處理階段事件並轉譯媒體
階段會發出許多事件。我們需要監聽 `STAGE_PARTICIPANT_STREAMS_ADDED` 和 `STAGE_PARTICIPANT_LEFT` 來回轉譯和移除頁面中的媒體。更詳盡的事件集列於[活動](web-publish-subscribe.md#web-publish-subscribe-concepts-events)中。
請注意，我們在這裡建立了四個協助程式函數，來協助管理必要的 DOM 元素：`setupParticipant`、`teardownParticipant`、`createVideoEl` 和 `createContainer`。
```
stage.on(StageEvents.STAGE_CONNECTION_STATE_CHANGED, (state) => {
connected = state === ConnectionState.CONNECTED;
if (connected) {
joining = false;
joinButton.style = "display: none";
leaveButton.style = "display: inline-block";
}
});
stage.on(
StageEvents.STAGE_PARTICIPANT_STREAMS_ADDED,
(participant, streams) => {
console.log("Participant Media Added: ", participant, streams);
let streamsToDisplay = streams;
if (participant.isLocal) {
// Ensure to exclude local audio streams, otherwise echo will occur
streamsToDisplay = streams.filter(
(stream) => stream.streamType === StreamType.VIDEO
);
}
const videoEl = setupParticipant(participant);
streamsToDisplay.forEach((stream) =>
videoEl.srcObject.addTrack(stream.mediaStreamTrack)
);
}
);
stage.on(StageEvents.STAGE_PARTICIPANT_LEFT, (participant) => {
console.log("Participant Left: ", participant);
teardownParticipant(participant);
});
// Helper functions for managing DOM
function setupParticipant({ isLocal, id }) {
const groupId = isLocal ? "local-media" : "remote-media";
const groupContainer = document.getElementById(groupId);
const participantContainerId = isLocal ? "local" : id;
const participantContainer = createContainer(participantContainerId);
const videoEl = createVideoEl(participantContainerId);
participantContainer.appendChild(videoEl);
groupContainer.appendChild(participantContainer);
return videoEl;
}
function teardownParticipant({ isLocal, id }) {
const groupId = isLocal ? "local-media" : "remote-media";
const groupContainer = document.getElementById(groupId);
const participantContainerId = isLocal ? "local" : id;
const participantDiv = document.getElementById(
participantContainerId + "-container"
);
if (!participantDiv) {
return;
}
groupContainer.removeChild(participantDiv);
}
function createVideoEl(id) {
const videoEl = document.createElement("video");
videoEl.id = id;
videoEl.autoplay = true;
videoEl.playsInline = true;
videoEl.srcObject = new MediaStream();
return videoEl;
}
function createContainer(id) {
const participantContainer = document.createElement("div");
participantContainer.classList = "participant-container";
participantContainer.id = id + "-container";
return participantContainer;
}
```
## 建立 JoinSage 5：加入階段
最終加入階段以完成 `joinStage` 函數！
```
try {
await stage.join();
} catch (err) {
joining = false;
connected = false;
console.error(err.message);
}
```
## 建立 leaveStage
定義 `leaveStage` 離開按鈕將調用的函數。
```
const leaveStage = async () => {
stage.leave();
joining = false;
connected = false;
};
```
## 初始化輸入事件處理常式
將新增一個最後的函數至 `app.js` 檔案。當載入頁面並建立事件處理常式以加入和離開階段時，會立即調用此函數。
```
const init = async () => {
try {
// Prevents issues on Safari/FF so devices are not blank
await navigator.mediaDevices.getUserMedia({ video: true, audio: true });
} catch (e) {
alert(
"Problem retrieving media! Enable camera and microphone permissions."
);
}
joinButton.addEventListener("click", () => {
joinStage();
});
leaveButton.addEventListener("click", () => {
leaveStage();
joinButton.style = "display: inline-block";
leaveButton.style = "display: none";
});
};
init(); // call the function
```
## 執行應用程式並提供權杖
此時，您可以在本地或與其他人分享網頁，[打開頁面](#getting-started-pub-sub-web-media)，然後輸入參與者權杖並加入階段。
## 後續步驟？
有關 npm、React 等的更詳細範例，請參閱 [IVS 廣播 SDK：網絡指南（即時串流指南）](broadcast-web.md)。
# 使用 IVS Android 廣播 SDK 發布和訂閱
Android
本節將引導您完成使用 Android 應用程式發布和訂閱階段的相關步驟。
## 建立檢視
首先使用自動建立的 `activity_main.xml` 檔案，來建立應用程式的簡單配置。配置包含一個可新增權杖的 `EditText`、一個加入 `Button`、一個可顯示階段狀態的 `TextView`，以及一個可切換發布的 `CheckBox`。
![\[為您的 Android 應用程式設定發布配置。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_Android_1.png)
以下是檢視背後的 XML：
```
```
我們在這裡引用了幾個字串 ID，因此，現在將建立整個 `strings.xml` 檔案：
```
BasicRealTime
Join
Leave
Participant Token
Publish
State: %1$s
```
將 XML 中的這些檢視連結至 `MainActivity.kt`:
```
import android.widget.Button
import android.widget.CheckBox
import android.widget.EditText
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
private lateinit var checkboxPublish: CheckBox
private lateinit var recyclerView: RecyclerView
private lateinit var buttonJoin: Button
private lateinit var textViewState: TextView
private lateinit var editTextToken: EditText
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
checkboxPublish = findViewById(R.id.main_publish_checkbox)
recyclerView = findViewById(R.id.main_recycler_view)
buttonJoin = findViewById(R.id.main_join)
textViewState = findViewById(R.id.main_state)
editTextToken = findViewById(R.id.main_token)
}
```
現在，將為 `RecyclerView` 建立項目檢視。若要執行此操作，在 `res/layout` 目錄上按一下滑鼠右鍵，然後選取**新增 > 配置資源檔案**。將此新檔案命名為 `item_stage_participant.xml`。
![\[為您的 Android 應用程式 RecyclerView 建立項目檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_Android_2.png)
此項目的配置很簡單：包含一個用於轉譯參與者影片串流的檢視，以及一個用於顯示參與者資訊的標籤清單：
![\[為您的 Android 應用程式 RecyclerView 建立項目檢視 – 標籤。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_Android_3.png)
下面是 XML：
```
```
此 XML 檔案擴充了尚未建立的類別 `ParticipantItem`。由於 XML 包括完整的命名空間，因此請務必將此 XML 檔案更新至您的命名空間。建立此類別並設定檢視，否則現在將其保留為空白。
建立一個新的 Kotlin 類別 `ParticipantItem`:
```
package com.amazonaws.ivs.realtime.basicrealtime
import android.content.Context
import android.util.AttributeSet
import android.widget.FrameLayout
import android.widget.TextView
import kotlin.math.roundToInt
class ParticipantItem @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0,
defStyleRes: Int = 0,
) : FrameLayout(context, attrs, defStyleAttr, defStyleRes) {
private lateinit var previewContainer: FrameLayout
private lateinit var textViewParticipantId: TextView
private lateinit var textViewPublish: TextView
private lateinit var textViewSubscribe: TextView
private lateinit var textViewVideoMuted: TextView
private lateinit var textViewAudioMuted: TextView
private lateinit var textViewAudioLevel: TextView
override fun onFinishInflate() {
super.onFinishInflate()
previewContainer = findViewById(R.id.participant_preview_container)
textViewParticipantId = findViewById(R.id.participant_participant_id)
textViewPublish = findViewById(R.id.participant_publishing)
textViewSubscribe = findViewById(R.id.participant_subscribed)
textViewVideoMuted = findViewById(R.id.participant_video_muted)
textViewAudioMuted = findViewById(R.id.participant_audio_muted)
textViewAudioLevel = findViewById(R.id.participant_audio_level)
}
}
```
## 許可
若要使用攝影機和麥克風，您需要向使用者請求許可。我們對此遵循標準許可流程：
```
override fun onStart() {
super.onStart()
requestPermission()
}
private val requestPermissionLauncher =
registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { permissions ->
if (permissions[Manifest.permission.CAMERA] == true && permissions[Manifest.permission.RECORD_AUDIO] == true) {
viewModel.permissionGranted() // we will add this later
}
}
private val permissions = listOf(
Manifest.permission.CAMERA,
Manifest.permission.RECORD_AUDIO,
)
private fun requestPermission() {
when {
this.hasPermissions(permissions) -> viewModel.permissionGranted() // we will add this later
else -> requestPermissionLauncher.launch(permissions.toTypedArray())
}
}
private fun Context.hasPermissions(permissions: List): Boolean {
return permissions.all {
ContextCompat.checkSelfPermission(this, it) == PackageManager.PERMISSION_GRANTED
}
}
```
## 應用程式狀態
我們的應用程式會在 `MainViewModel.kt` 中本機追蹤參與者，並且使用 Kotlin 的 [StateFlow](https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines.flow/-state-flow/) 將狀態傳回至 `MainActivity`。
建立一個新的 Kotlin 類別 `MainViewModel`:
```
package com.amazonaws.ivs.realtime.basicrealtime
import android.app.Application
import androidx.lifecycle.AndroidViewModel
class MainViewModel(application: Application) : AndroidViewModel(application), Stage.Strategy, StageRenderer {
}
```
將在 `MainActivity.kt` 中管理檢視模型：
```
import androidx.activity.viewModels
private val viewModel: MainViewModel by viewModels()
```
若要使用 `AndroidViewModel` 和這些 Kotlin `ViewModel` 延伸，您需要將以下內容新增至模組的 `build.gradle` 檔案:
```
implementation 'androidx.core:core-ktx:1.10.1'
implementation "androidx.activity:activity-ktx:1.7.2"
implementation 'androidx.appcompat:appcompat:1.6.1'
implementation 'com.google.android.material:material:1.10.0'
implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"
def lifecycle_version = "2.6.1"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
```
### RecyclerView Adapter
我們將建立一個簡單的 `RecyclerView.Adapter` 子類別，以追蹤參與者並更新階段事件的 `RecyclerView`。首先，需要一個代表參與者的類別。建立一個新的 Kotlin 類別 `StageParticipant`:
```
package com.amazonaws.ivs.realtime.basicrealtime
import com.amazonaws.ivs.broadcast.Stage
import com.amazonaws.ivs.broadcast.StageStream
class StageParticipant(val isLocal: Boolean, var participantId: String?) {
var publishState = Stage.PublishState.NOT_PUBLISHED
var subscribeState = Stage.SubscribeState.NOT_SUBSCRIBED
var streams = mutableListOf()
val stableID: String
get() {
return if (isLocal) {
"LocalUser"
} else {
requireNotNull(participantId)
}
}
}
```
我們將使用接下來會建立的 `ParticipantAdapter` 類別中的此類別。首先定義類別，並建立用於追蹤參與者的變數：
```
package com.amazonaws.ivs.realtime.basicrealtime
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
class ParticipantAdapter : RecyclerView.Adapter() {
private val participants = mutableListOf()
```
此外還必須定義 `RecyclerView.ViewHolder`，再實作其餘的覆寫：
```
class ViewHolder(val participantItem: ParticipantItem) : RecyclerView.ViewHolder(participantItem)
```
使用此類別，可實作標準 `RecyclerView.Adapter` 覆寫：
```
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val item = LayoutInflater.from(parent.context)
.inflate(R.layout.item_stage_participant, parent, false) as ParticipantItem
return ViewHolder(item)
}
override fun getItemCount(): Int {
return participants.size
}
override fun getItemId(position: Int): Long =
participants[position]
.stableID
.hashCode()
.toLong()
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
return holder.participantItem.bind(participants[position])
}
override fun onBindViewHolder(holder: ViewHolder, position: Int, payloads: MutableList) {
val updates = payloads.filterIsInstance()
if (updates.isNotEmpty()) {
updates.forEach { holder.participantItem.bind(it) // implemented later }
} else {
super.onBindViewHolder(holder, position, payloads)
}
}
```
最後，我們新增一些新的方法，當對參與者做出變更時，將會從 `MainViewModel` 中呼叫這些方法。這些方法是轉接器上的標準 CRUD 作業。
```
fun participantJoined(participant: StageParticipant) {
participants.add(participant)
notifyItemInserted(participants.size - 1)
}
fun participantLeft(participantId: String) {
val index = participants.indexOfFirst { it.participantId == participantId }
if (index != -1) {
participants.removeAt(index)
notifyItemRemoved(index)
}
}
fun participantUpdated(participantId: String?, update: (participant: StageParticipant) -> Unit) {
val index = participants.indexOfFirst { it.participantId == participantId }
if (index != -1) {
update(participants[index])
notifyItemChanged(index, participants[index])
}
}
```
回到 `MainViewModel`，我們需要建立並保留此轉接器的參考：
```
internal val participantAdapter = ParticipantAdapter()
```
## 階段狀態
還需要追蹤 `MainViewModel` 內的一些階段狀態。現在，我們來定義這些屬性：
```
private val _connectionState = MutableStateFlow(Stage.ConnectionState.DISCONNECTED)
val connectionState = _connectionState.asStateFlow()
private var publishEnabled: Boolean = false
set(value) {
field = value
// Because the strategy returns the value of `checkboxPublish.isChecked`, just call `refreshStrategy`.
stage?.refreshStrategy()
}
private var deviceDiscovery: DeviceDiscovery? = null
private var stage: Stage? = null
private var streams = mutableListOf()
```
若要在加入階段之前查看您自己的預覽，我們會立即建立本機參與者：
```
init {
deviceDiscovery = DeviceDiscovery(application)
// Create a local participant immediately to render our camera preview and microphone stats
val localParticipant = StageParticipant(true, null)
participantAdapter.participantJoined(localParticipant)
}
```
我們希望確保在清除 `ViewModel` 時也清除這些資源。我們會馬上覆寫 `onCleared()`，因此不要忘了清除這些資源。
```
override fun onCleared() {
stage?.release()
deviceDiscovery?.release()
deviceDiscovery = null
super.onCleared()
}
```
現在，一旦授予許可，我們會填充本機 `streams`，實作之前呼叫的 `permissionsGranted` 方法：
```
internal fun permissionGranted() {
val deviceDiscovery = deviceDiscovery ?: return
streams.clear()
val devices = deviceDiscovery.listLocalDevices()
// Camera
devices
.filter { it.descriptor.type == Device.Descriptor.DeviceType.CAMERA }
.maxByOrNull { it.descriptor.position == Device.Descriptor.Position.FRONT }
?.let { streams.add(ImageLocalStageStream(it)) }
// Microphone
devices
.filter { it.descriptor.type == Device.Descriptor.DeviceType.MICROPHONE }
.maxByOrNull { it.descriptor.isDefault }
?.let { streams.add(AudioLocalStageStream(it)) }
stage?.refreshStrategy()
// Update our local participant with these new streams
participantAdapter.participantUpdated(null) {
it.streams.clear()
it.streams.addAll(streams)
}
}
```
## 實作階段 SDK
以下是三個以即時功能為基礎的核心[概念](android-publish-subscribe.md#android-publish-subscribe-concepts)：階段、策略和轉譯器。設計目標是盡可能減少打造工作產品所需的用戶端邏輯數量。
### Stage.Strategy
`Stage.Strategy` 實作很簡單：
```
override fun stageStreamsToPublishForParticipant(
stage: Stage,
participantInfo: ParticipantInfo
): MutableList {
// Return the camera and microphone to be published.
// This is only called if `shouldPublishFromParticipant` returns true.
return streams
}
override fun shouldPublishFromParticipant(stage: Stage, participantInfo: ParticipantInfo): Boolean {
return publishEnabled
}
override fun shouldSubscribeToParticipant(stage: Stage, participantInfo: ParticipantInfo): Stage.SubscribeType {
// Subscribe to both audio and video for all publishing participants.
return Stage.SubscribeType.AUDIO_VIDEO
}
```
總而言之，根據內部的 `publishEnabled` 狀態來發布，如果要發布，我們會發布之前收集的串流。最後，針對此範例，始終會訂閱其他參與者，同時接收其音訊和影片。
### StageRenderer
`StageRenderer` 實作也非常簡單，但要考慮包含相當多程式碼的函數數量。當 SDK 通知我們有關參與者的變更時，此轉譯器中的一般方法是更新 `ParticipantAdapter`。在某些情況下，對於本機參與者的處理方式有所不同，因為我們已決定自行管理他們，以便在他們加入之前查看其攝影機預覽。
```
override fun onError(exception: BroadcastException) {
Toast.makeText(getApplication(), "onError ${exception.localizedMessage}", Toast.LENGTH_LONG).show()
Log.e("BasicRealTime", "onError $exception")
}
override fun onConnectionStateChanged(
stage: Stage,
connectionState: Stage.ConnectionState,
exception: BroadcastException?
) {
_connectionState.value = connectionState
}
override fun onParticipantJoined(stage: Stage, participantInfo: ParticipantInfo) {
if (participantInfo.isLocal) {
// If this is the local participant joining the stage, update the participant with a null ID because we
// manually added that participant when setting up our preview
participantAdapter.participantUpdated(null) {
it.participantId = participantInfo.participantId
}
} else {
// If they are not local, add them normally
participantAdapter.participantJoined(
StageParticipant(
participantInfo.isLocal,
participantInfo.participantId
)
)
}
}
override fun onParticipantLeft(stage: Stage, participantInfo: ParticipantInfo) {
if (participantInfo.isLocal) {
// If this is the local participant leaving the stage, update the ID but keep it around because
// we want to keep the camera preview active
participantAdapter.participantUpdated(participantInfo.participantId) {
it.participantId = null
}
} else {
// If they are not local, have them leave normally
participantAdapter.participantLeft(participantInfo.participantId)
}
}
override fun onParticipantPublishStateChanged(
stage: Stage,
participantInfo: ParticipantInfo,
publishState: Stage.PublishState
) {
// Update the publishing state of this participant
participantAdapter.participantUpdated(participantInfo.participantId) {
it.publishState = publishState
}
}
override fun onParticipantSubscribeStateChanged(
stage: Stage,
participantInfo: ParticipantInfo,
subscribeState: Stage.SubscribeState
) {
// Update the subscribe state of this participant
participantAdapter.participantUpdated(participantInfo.participantId) {
it.subscribeState = subscribeState
}
}
override fun onStreamsAdded(stage: Stage, participantInfo: ParticipantInfo, streams: MutableList) {
// We don't want to take any action for the local participant because we track those streams locally
if (participantInfo.isLocal) {
return
}
// For remote participants, add these new streams to that participant's streams array.
participantAdapter.participantUpdated(participantInfo.participantId) {
it.streams.addAll(streams)
}
}
override fun onStreamsRemoved(stage: Stage, participantInfo: ParticipantInfo, streams: MutableList) {
// We don't want to take any action for the local participant because we track those streams locally
if (participantInfo.isLocal) {
return
}
// For remote participants, remove these streams from that participant's streams array.
participantAdapter.participantUpdated(participantInfo.participantId) {
it.streams.removeAll(streams)
}
}
override fun onStreamsMutedChanged(
stage: Stage,
participantInfo: ParticipantInfo,
streams: MutableList
) {
// We don't want to take any action for the local participant because we track those streams locally
if (participantInfo.isLocal) {
return
}
// For remote participants, notify the adapter that the participant has been updated. There is no need to modify
// the `streams` property on the `StageParticipant` because it is the same `StageStream` instance. Just
// query the `isMuted` property again.
participantAdapter.participantUpdated(participantInfo.participantId) {}
}
```
## 實作自訂 RecyclerView LayoutManager
配置不同數量的參與者可能很複雜。您希望他們佔用整個父檢視的框架，但不想單獨處理每個參與者配置。為了簡化這一點，我們將逐步實作 `RecyclerView.LayoutManager`。
建立另一個新類別 `StageLayoutManager`，這應當會延伸 `GridLayoutManager`。設計此類別的目的是，根據以流程為基礎的資料列/資料欄配置中的參與者人數，來計算每個參與者的配置。每個資料列的高度與其他資料列相同，但每個資料列的寬度可能有所差異。請參閱 `layouts` 變數上方的程式碼註解，描述了如何自訂此行為。
```
package com.amazonaws.ivs.realtime.basicrealtime
import android.content.Context
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
class StageLayoutManager(context: Context?) : GridLayoutManager(context, 6) {
companion object {
/**
* This 2D array contains the description of how the grid of participants should be rendered
* The index of the 1st dimension is the number of participants needed to active that configuration
* Meaning if there is 1 participant, index 0 will be used. If there are 5 participants, index 4 will be used.
*
* The 2nd dimension is a description of the layout. The length of the array is the number of rows that
* will exist, and then each number within that array is the number of columns in each row.
*
* See the code comments next to each index for concrete examples.
*
* This can be customized to fit any layout configuration needed.
*/
val layouts: List> = listOf(
// 1 participant
listOf(1), // 1 row, full width
// 2 participants
listOf(1, 1), // 2 rows, all columns are full width
// 3 participants
listOf(1, 2), // 2 rows, first row's column is full width then 2nd row's columns are 1/2 width
// 4 participants
listOf(2, 2), // 2 rows, all columns are 1/2 width
// 5 participants
listOf(1, 2, 2), // 3 rows, first row's column is full width, 2nd and 3rd row's columns are 1/2 width
// 6 participants
listOf(2, 2, 2), // 3 rows, all column are 1/2 width
// 7 participants
listOf(2, 2, 3), // 3 rows, 1st and 2nd row's columns are 1/2 width, 3rd row's columns are 1/3rd width
// 8 participants
listOf(2, 3, 3),
// 9 participants
listOf(3, 3, 3),
// 10 participants
listOf(2, 3, 2, 3),
// 11 participants
listOf(2, 3, 3, 3),
// 12 participants
listOf(3, 3, 3, 3),
)
}
init {
spanSizeLookup = object : SpanSizeLookup() {
override fun getSpanSize(position: Int): Int {
if (itemCount <= 0) {
return 1
}
// Calculate the row we're in
val config = layouts[itemCount - 1]
var row = 0
var curPosition = position
while (curPosition - config[row] >= 0) {
curPosition -= config[row]
row++
}
// spanCount == max spans, config[row] = number of columns we want
// So spanCount / config[row] would be something like 6 / 3 if we want 3 columns.
// So this will take up 2 spans, with a max of 6 is 1/3rd of the view.
return spanCount / config[row]
}
}
}
override fun onLayoutChildren(recycler: RecyclerView.Recycler?, state: RecyclerView.State?) {
if (itemCount <= 0 || state?.isPreLayout == true) return
val parentHeight = height
val itemHeight = parentHeight / layouts[itemCount - 1].size // height divided by number of rows.
// Set the height of each view based on how many rows exist for the current participant count.
for (i in 0 until childCount) {
val child = getChildAt(i) ?: continue
val layoutParams = child.layoutParams as RecyclerView.LayoutParams
if (layoutParams.height != itemHeight) {
layoutParams.height = itemHeight
child.layoutParams = layoutParams
}
}
// After we set the height for all our views, call super.
// This works because our RecyclerView can not scroll and all views are always visible with stable IDs.
super.onLayoutChildren(recycler, state)
}
override fun canScrollVertically(): Boolean = false
override fun canScrollHorizontally(): Boolean = false
}
```
回到 `MainActivity.kt`，我們需要為 `RecyclerView` 設定轉接器和配置管理器：
```
// In onCreate after setting recyclerView.
recyclerView.layoutManager = StageLayoutManager(this)
recyclerView.adapter = viewModel.participantAdapter
```
## 掛接 UI 動作
即將結束；我們只需掛接幾個 UI 動作。
首先，讓 `MainActivity` 觀測 `MainViewModel` 中的 `StateFlow` 變更：
```
// At the end of your onCreate method
lifecycleScope.launch {
repeatOnLifecycle(Lifecycle.State.CREATED) {
viewModel.connectionState.collect { state ->
buttonJoin.setText(if (state == ConnectionState.DISCONNECTED) R.string.join else R.string.leave)
textViewState.text = getString(R.string.state, state.name)
}
}
}
```
接著，將接聽程式新增至加入按鈕和發布核取方塊：
```
buttonJoin.setOnClickListener {
viewModel.joinStage(editTextToken.text.toString())
}
checkboxPublish.setOnCheckedChangeListener { _, isChecked ->
viewModel.setPublishEnabled(isChecked)
}
```
上述兩個呼叫功能均位於 `MainViewModel`，現在將在此實作：
```
internal fun joinStage(token: String) {
if (_connectionState.value != Stage.ConnectionState.DISCONNECTED) {
// If we're already connected to a stage, leave it.
stage?.leave()
} else {
if (token.isEmpty()) {
Toast.makeText(getApplication(), "Empty Token", Toast.LENGTH_SHORT).show()
return
}
try {
// Destroy the old stage first before creating a new one.
stage?.release()
val stage = Stage(getApplication(), token, this)
stage.addRenderer(this)
stage.join()
this.stage = stage
} catch (e: BroadcastException) {
Toast.makeText(getApplication(), "Failed to join stage ${e.localizedMessage}", Toast.LENGTH_LONG).show()
e.printStackTrace()
}
}
}
internal fun setPublishEnabled(enabled: Boolean) {
publishEnabled = enabled
}
```
## 轉譯參與者
最後，我們需要將從 SDK 接收的資料，轉譯到之前建立的參與者項目上。我們已經完成了 `RecyclerView` 邏輯，因此只需實作 `ParticipantItem` 中的 `bind` API。
從新增空函數開始，然後逐步實作：
```
fun bind(participant: StageParticipant) {
}
```
首先，將處理簡易狀態、參與者 ID、發布狀態和訂閱狀態。對於這些，只需直接更新 `TextViews`：
```
val participantId = if (participant.isLocal) {
"You (${participant.participantId ?: "Disconnected"})"
} else {
participant.participantId
}
textViewParticipantId.text = participantId
textViewPublish.text = participant.publishState.name
textViewSubscribe.text = participant.subscribeState.name
```
接著，將更新音訊和影片靜音狀態。為取得靜音狀態，需要從串流陣列中找到 `ImageDevice` 和 `AudioDevice`。為優化效能，我們會記住上次連接的裝置 ID。
```
// This belongs outside the `bind` API.
private var imageDeviceUrn: String? = null
private var audioDeviceUrn: String? = null
// This belongs inside the `bind` API.
val newImageStream = participant
.streams
.firstOrNull { it.device is ImageDevice }
textViewVideoMuted.text = if (newImageStream != null) {
if (newImageStream.muted) "Video muted" else "Video not muted"
} else {
"No video stream"
}
val newAudioStream = participant
.streams
.firstOrNull { it.device is AudioDevice }
textViewAudioMuted.text = if (newAudioStream != null) {
if (newAudioStream.muted) "Audio muted" else "Audio not muted"
} else {
"No audio stream"
}
```
最後，要轉譯 `imageDevice` 的預覽：
```
if (newImageStream?.device?.descriptor?.urn != imageDeviceUrn) {
// If the device has changed, remove all subviews from the preview container
previewContainer.removeAllViews()
(newImageStream?.device as? ImageDevice)?.let {
val preview = it.getPreviewView(BroadcastConfiguration.AspectMode.FIT)
previewContainer.addView(preview)
preview.layoutParams = FrameLayout.LayoutParams(
FrameLayout.LayoutParams.MATCH_PARENT,
FrameLayout.LayoutParams.MATCH_PARENT
)
}
}
imageDeviceUrn = newImageStream?.device?.descriptor?.urn
```
然後顯示 `audioDevice` 中的音訊統計資料：
```
if (newAudioStream?.device?.descriptor?.urn != audioDeviceUrn) {
(newAudioStream?.device as? AudioDevice)?.let {
it.setStatsCallback { _, rms ->
textViewAudioLevel.text = "Audio Level: ${rms.roundToInt()} dB"
}
}
}
audioDeviceUrn = newAudioStream?.device?.descriptor?.urn
```
# 使用 IVS iOS 廣播 SDK 發布和訂閱
iOS
本節將引導您完成使用 iOS 應用程式發布和訂閱階段的相關步驟。
## 建立檢視
首先，使用自動建立用於匯入 `AmazonIVSBroadcast` 的 `ViewController.swift` 檔案，然後新增一些要連結的 `@IBOutlets`：
```
import AmazonIVSBroadcast
class ViewController: UIViewController {
@IBOutlet private var textFieldToken: UITextField!
@IBOutlet private var buttonJoin: UIButton!
@IBOutlet private var labelState: UILabel!
@IBOutlet private var switchPublish: UISwitch!
@IBOutlet private var collectionViewParticipants: UICollectionView!
```
現在，建立這些檢視，並在 `Main.storyboard` 中將其連結。以下是將使用的檢視結構：
![\[使用 Main.storyboard 來建立 iOS 檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_1.png)
若是 AutoLayout 組態，需要自訂三個檢視。第一個檢視是**集合檢視參與者** (`UICollectionView`)。將**前導**、**尾隨**和**底部**繫結至**安全區域**。同時將**頂部**繫結至**控制容器**。
![\[自訂 iOS 集合檢視參與者的檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_2.png)
第二個檢視是**控制容器**。將**前導**、**尾隨**和**頂部**繫結至**安全區域**。
![\[自訂 iOS 控制容器檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_3.png)
第三個和最後一個檢視是**垂直堆疊檢視**。將**頂部**、**前導**、**尾隨**和**底部**繫結至**父檢視**。針對樣式，將間距設定為 8，而不是 0。
![\[自訂 iOS 垂直堆疊檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_4.png)
**UIStackViews** 會處理其餘檢視的配置。針對所有三個 **UIStackViews**，在**對齊**和**分佈**時使用**填滿**。
![\[使用 UIStackViews 自訂其餘的 iOS 檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_5.png)
最後，將這些檢視連結至 `ViewController`。從上方映射下列檢視：
+ **文字欄位加入**繫結至 `textFieldToken`。
+ **按鈕加入**繫結至 `buttonJoin`。
+ **標籤狀態**繫結至 `labelState`。
+ **切換發布**繫結至 `switchPublish`。
+ **集合檢視參與者**繫結至 `collectionViewParticipants`。
同時還會將**集合檢視參與者**項目的 `dataSource` 設定為擁有的 `ViewController`:
![\[若是 iOS 應用程式，還會設定集合檢視參與者的資料來源。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_6.png)
現在，建立要在其中轉譯參與者的 `UICollectionViewCell` 子類別。首先，建立一個新的 **Cocoa Touch 類別**檔案：
![\[建立 UICollectionViewCell，以轉譯 iOS 即時參與者。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_7.png)
將其命名為 `ParticipantUICollectionViewCell`，然後使其成為 Swift 中 `UICollectionViewCell` 的子類別。再次從 Swift 檔案開始，建立要連結的 `@IBOutlets`：
```
import AmazonIVSBroadcast
class ParticipantCollectionViewCell: UICollectionViewCell {
@IBOutlet private var viewPreviewContainer: UIView!
@IBOutlet private var labelParticipantId: UILabel!
@IBOutlet private var labelSubscribeState: UILabel!
@IBOutlet private var labelPublishState: UILabel!
@IBOutlet private var labelVideoMuted: UILabel!
@IBOutlet private var labelAudioMuted: UILabel!
@IBOutlet private var labelAudioVolume: UILabel!
```
在關聯的 XIB 檔案中，建立此檢視階層：
![\[在關聯的 XIB 檔案中，建立 iOS 檢視階層。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_8.png)
針對 AutoLayout，將再次修改三個檢視。第一個檢視是**檢視預覽容器**。將**尾隨**、**前導**、**頂部**和**底部**設定為**參與者集合檢視儲存格**。
![\[自訂 iOS 檢視預覽容器檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_9.png)
第二個檢視是**檢視**。將**前導**和**頂部**設定為**參與者集合檢視儲存格**，並將該值變更為 4。
![\[自訂 iOS 檢視的檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_10.png)
第三個檢視是**堆疊檢視**。將 **Trailing**、**Leading**、**Top** 和 **Bottom** 設定為 **Superview**，並將值變更為 4。
![\[自訂 iOS 堆疊檢視的檢視。\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_11.png)
## 許可和閒置計時器
回到 `ViewController`，將停用系統閒置計時器，以免在使用應用程式時，裝置進入睡眠狀態：
```
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
// Prevent the screen from turning off during a call.
UIApplication.shared.isIdleTimerDisabled = true
}
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
UIApplication.shared.isIdleTimerDisabled = false
}
```
接著，請求系統的攝影機和麥克風許可：
```
private func checkPermissions() {
checkOrGetPermission(for: .video) { [weak self] granted in
guard granted else {
print("Video permission denied")
return
}
self?.checkOrGetPermission(for: .audio) { [weak self] granted in
guard granted else {
print("Audio permission denied")
return
}
self?.setupLocalUser() // we will cover this later
}
}
}
private func checkOrGetPermission(for mediaType: AVMediaType, _ result: @escaping (Bool) -> Void) {
func mainThreadResult(_ success: Bool) {
DispatchQueue.main.async {
result(success)
}
}
switch AVCaptureDevice.authorizationStatus(for: mediaType) {
case .authorized: mainThreadResult(true)
case .notDetermined:
AVCaptureDevice.requestAccess(for: mediaType) { granted in
mainThreadResult(granted)
}
case .denied, .restricted: mainThreadResult(false)
@unknown default: mainThreadResult(false)
}
}
```
## 應用程式狀態
需要設定 `collectionViewParticipants` 以及之前建立的配置檔案：
```
override func viewDidLoad() {
super.viewDidLoad()
// We render everything to exactly the frame, so don't allow scrolling.
collectionViewParticipants.isScrollEnabled = false
collectionViewParticipants.register(UINib(nibName: "ParticipantCollectionViewCell", bundle: .main), forCellWithReuseIdentifier: "ParticipantCollectionViewCell")
}
```
為了代表每個參與者，我們建立了一個稱為 `StageParticipant` 的簡單結構。這可包含在 `ViewController.swift` 檔案中，或建立新的檔案。
```
import Foundation
import AmazonIVSBroadcast
struct StageParticipant {
let isLocal: Bool
var participantId: String?
var publishState: IVSParticipantPublishState = .notPublished
var subscribeState: IVSParticipantSubscribeState = .notSubscribed
var streams: [IVSStageStream] = []
init(isLocal: Bool, participantId: String?) {
self.isLocal = isLocal
self.participantId = participantId
}
}
```
為了追蹤這些參與者，我們將其陣列做為私有屬性保留在 `ViewController` 中:
```
private var participants = [StageParticipant]()
```
此屬性將用於支援之前從分鏡腳本連結的 `UICollectionViewDataSource`：
```
extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return participants.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ParticipantCollectionViewCell", for: indexPath) as? ParticipantCollectionViewCell {
cell.set(participant: participants[indexPath.row])
return cell
} else {
fatalError("Couldn't load custom cell type 'ParticipantCollectionViewCell'")
}
}
}
```
若要在加入階段之前查看您自己的預覽，我們會立即建立本機參與者：
```
override func viewDidLoad() {
/* existing UICollectionView code */
participants.append(StageParticipant(isLocal: true, participantId: nil))
}
```
這會導致在應用程式執行後，代表本機參與者立即轉譯參與者儲存格。
使用者希望能夠在加入階段之前看到自己，因此，接下來我們實作 `setupLocalUser()` 方法，可從稍早的許可處理程式碼中呼叫。將攝影機和麥克風參考做為 `IVSLocalStageStream` 物件來存放。
```
private var streams = [IVSLocalStageStream]()
private let deviceDiscovery = IVSDeviceDiscovery()
private func setupLocalUser() {
// Gather our camera and microphone once permissions have been granted
let devices = deviceDiscovery.listLocalDevices()
streams.removeAll()
if let camera = devices.compactMap({ $0 as? IVSCamera }).first {
streams.append(IVSLocalStageStream(device: camera))
// Use a front camera if available.
if let frontSource = camera.listAvailableInputSources().first(where: { $0.position == .front }) {
camera.setPreferredInputSource(frontSource)
}
}
if let mic = devices.compactMap({ $0 as? IVSMicrophone }).first {
streams.append(IVSLocalStageStream(device: mic))
}
participants[0].streams = streams
participantsChanged(index: 0, changeType: .updated)
}
```
在這裡透過 SDK 找到了裝置的攝影機和麥克風，並將其存放在本機 `streams` 物件中，然後將第一個參與者 (我們之前建立的本機參與者) 的 `streams` 陣列指派到 `streams`。最後，呼叫 `index` 為 0，以及 `changeType` 為 `updated` 的 `participantsChanged`。該函數是透過良好的動畫更新 `UICollectionView` 的輔助程式函數。這是呈現的外觀：
```
private func participantsChanged(index: Int, changeType: ChangeType) {
switch changeType {
case .joined:
collectionViewParticipants?.insertItems(at: [IndexPath(item: index, section: 0)])
case .updated:
// Instead of doing reloadItems, just grab the cell and update it ourselves. It saves a create/destroy of a cell
// and more importantly fixes some UI flicker. We disable scrolling so the index path per cell
// never changes.
if let cell = collectionViewParticipants?.cellForItem(at: IndexPath(item: index, section: 0)) as? ParticipantCollectionViewCell {
cell.set(participant: participants[index])
}
case .left:
collectionViewParticipants?.deleteItems(at: [IndexPath(item: index, section: 0)])
}
}
```
別擔心 `cell.set`；稍後會處理，這就是我們將根據參與者轉譯儲存格內容的地方。
`ChangeType` 是一個簡單的列舉：
```
enum ChangeType {
case joined, updated, left
}
```
最後，想要追蹤階段是否已建立連線。使用一個簡單的 `bool` 來追蹤，在其自行更新時，會自動更新 UI。
```
private var connectingOrConnected = false {
didSet {
buttonJoin.setTitle(connectingOrConnected ? "Leave" : "Join", for: .normal)
buttonJoin.tintColor = connectingOrConnected ? .systemRed : .systemBlue
}
}
```
## 實作階段 SDK
以下是三個以即時功能為基礎的核心[概念](ios-publish-subscribe.md#ios-publish-subscribe-concepts)：階段、策略和轉譯器。設計目標是盡可能減少打造工作產品所需的用戶端邏輯數量。
### IVSStageStrategy
`IVSStageStrategy` 實作很簡單：
```
extension ViewController: IVSStageStrategy {
func stage(_ stage: IVSStage, streamsToPublishForParticipant participant: IVSParticipantInfo) -> [IVSLocalStageStream] {
// Return the camera and microphone to be published.
// This is only called if `shouldPublishParticipant` returns true.
return streams
}
func stage(_ stage: IVSStage, shouldPublishParticipant participant: IVSParticipantInfo) -> Bool {
// Our publish status is based directly on the UISwitch view
return switchPublish.isOn
}
func stage(_ stage: IVSStage, shouldSubscribeToParticipant participant: IVSParticipantInfo) -> IVSStageSubscribeType {
// Subscribe to both audio and video for all publishing participants.
return .audioVideo
}
}
```
總而言之，只有在發布切換按鈕處於「開啟」位置時才會發布，如果要發布，我們會發布之前收集的串流。最後，針對此範例，始終會訂閱其他參與者，同時接收其音訊和影片。
### IVSStageRenderer
`IVSStageRenderer` 實作也非常簡單，但要考慮包含相當多程式碼的函數數量。當 SDK 通知我們有關參與者的變更時，此轉譯器中的一般方法是更新我們的 `participants` 陣列。在某些情況下，對於本機參與者的處理方式有所不同，因為我們已決定自行管理他們，以便在他們加入之前查看其攝影機預覽。
```
extension ViewController: IVSStageRenderer {
func stage(_ stage: IVSStage, didChange connectionState: IVSStageConnectionState, withError error: Error?) {
labelState.text = connectionState.text
connectingOrConnected = connectionState != .disconnected
}
func stage(_ stage: IVSStage, participantDidJoin participant: IVSParticipantInfo) {
if participant.isLocal {
// If this is the local participant joining the Stage, update the first participant in our array because we
// manually added that participant when setting up our preview
participants[0].participantId = participant.participantId
participantsChanged(index: 0, changeType: .updated)
} else {
// If they are not local, add them to the array as a newly joined participant.
participants.append(StageParticipant(isLocal: false, participantId: participant.participantId))
participantsChanged(index: (participants.count - 1), changeType: .joined)
}
}
func stage(_ stage: IVSStage, participantDidLeave participant: IVSParticipantInfo) {
if participant.isLocal {
// If this is the local participant leaving the Stage, update the first participant in our array because
// we want to keep the camera preview active
participants[0].participantId = nil
participantsChanged(index: 0, changeType: .updated)
} else {
// If they are not local, find their index and remove them from the array.
if let index = participants.firstIndex(where: { $0.participantId == participant.participantId }) {
participants.remove(at: index)
participantsChanged(index: index, changeType: .left)
}
}
}
func stage(_ stage: IVSStage, participant: IVSParticipantInfo, didChange publishState: IVSParticipantPublishState) {
// Update the publishing state of this participant
mutatingParticipant(participant.participantId) { data in
data.publishState = publishState
}
}
func stage(_ stage: IVSStage, participant: IVSParticipantInfo, didChange subscribeState: IVSParticipantSubscribeState) {
// Update the subscribe state of this participant
mutatingParticipant(participant.participantId) { data in
data.subscribeState = subscribeState
}
}
func stage(_ stage: IVSStage, participant: IVSParticipantInfo, didChangeMutedStreams streams: [IVSStageStream]) {
// We don't want to take any action for the local participant because we track those streams locally
if participant.isLocal { return }
// For remote participants, notify the UICollectionView that they have updated. There is no need to modify
// the `streams` property on the `StageParticipant` because it is the same `IVSStageStream` instance. Just
// query the `isMuted` property again.
if let index = participants.firstIndex(where: { $0.participantId == participant.participantId }) {
participantsChanged(index: index, changeType: .updated)
}
}
func stage(_ stage: IVSStage, participant: IVSParticipantInfo, didAdd streams: [IVSStageStream]) {
// We don't want to take any action for the local participant because we track those streams locally
if participant.isLocal { return }
// For remote participants, add these new streams to that participant's streams array.
mutatingParticipant(participant.participantId) { data in
data.streams.append(contentsOf: streams)
}
}
func stage(_ stage: IVSStage, participant: IVSParticipantInfo, didRemove streams: [IVSStageStream]) {
// We don't want to take any action for the local participant because we track those streams locally
if participant.isLocal { return }
// For remote participants, remove these streams from that participant's streams array.
mutatingParticipant(participant.participantId) { data in
let oldUrns = streams.map { $0.device.descriptor().urn }
data.streams.removeAll(where: { stream in
return oldUrns.contains(stream.device.descriptor().urn)
})
}
}
// A helper function to find a participant by its ID, mutate that participant, and then update the UICollectionView accordingly.
private func mutatingParticipant(_ participantId: String?, modifier: (inout StageParticipant) -> Void) {
guard let index = participants.firstIndex(where: { $0.participantId == participantId }) else {
fatalError("Something is out of sync, investigate if this was a sample app or SDK issue.")
}
var participant = participants[index]
modifier(&participant)
participants[index] = participant
participantsChanged(index: index, changeType: .updated)
}
}
```
此程式碼使用延伸，將連線狀態轉換為易讀的文字：
```
extension IVSStageConnectionState {
var text: String {
switch self {
case .disconnected: return "Disconnected"
case .connecting: return "Connecting"
case .connected: return "Connected"
@unknown default: fatalError()
}
}
}
```
## 實作自訂 UICollectionViewLayout
配置不同數量的參與者可能很複雜。您希望他們佔用整個父檢視的框架，但不想單獨處理每個參與者配置。為了簡化這一點，我們將逐步實作 `UICollectionViewLayout`。
建立另一個新檔案 `ParticipantCollectionViewLayout.swift`，這應當會延伸 `UICollectionViewLayout`。此類別會使用另一個稱為 `StageLayoutCalculator` 類別，我們很快會介紹。該類別會接收針對每個參與者計算的影格值，然後產生必要的 `UICollectionViewLayoutAttributes` 物件。
```
import Foundation
import UIKit
/**
Code modified from https://developer.apple.com/documentation/uikit/views_and_controls/collection_views/layouts/customizing_collection_view_layouts?language=objc
*/
class ParticipantCollectionViewLayout: UICollectionViewLayout {
private let layoutCalculator = StageLayoutCalculator()
private var contentBounds = CGRect.zero
private var cachedAttributes = [UICollectionViewLayoutAttributes]()
override func prepare() {
super.prepare()
guard let collectionView = collectionView else { return }
cachedAttributes.removeAll()
contentBounds = CGRect(origin: .zero, size: collectionView.bounds.size)
layoutCalculator.calculateFrames(participantCount: collectionView.numberOfItems(inSection: 0),
width: collectionView.bounds.size.width,
height: collectionView.bounds.size.height,
padding: 4)
.enumerated()
.forEach { (index, frame) in
let attributes = UICollectionViewLayoutAttributes(forCellWith: IndexPath(item: index, section: 0))
attributes.frame = frame
cachedAttributes.append(attributes)
contentBounds = contentBounds.union(frame)
}
}
override var collectionViewContentSize: CGSize {
return contentBounds.size
}
override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
guard let collectionView = collectionView else { return false }
return !newBounds.size.equalTo(collectionView.bounds.size)
}
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
return cachedAttributes[indexPath.item]
}
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
var attributesArray = [UICollectionViewLayoutAttributes]()
// Find any cell that sits within the query rect.
guard let lastIndex = cachedAttributes.indices.last, let firstMatchIndex = binSearch(rect, start: 0, end: lastIndex) else {
return attributesArray
}
// Starting from the match, loop up and down through the array until all the attributes
// have been added within the query rect.
for attributes in cachedAttributes[..= rect.minY else { break }
attributesArray.append(attributes)
}
for attributes in cachedAttributes[firstMatchIndex...] {
guard attributes.frame.minY <= rect.maxY else { break }
attributesArray.append(attributes)
}
return attributesArray
}
// Perform a binary search on the cached attributes array.
func binSearch(_ rect: CGRect, start: Int, end: Int) -> Int? {
if end < start { return nil }
let mid = (start + end) / 2
let attr = cachedAttributes[mid]
if attr.frame.intersects(rect) {
return mid
} else {
if attr.frame.maxY < rect.minY {
return binSearch(rect, start: (mid + 1), end: end)
} else {
return binSearch(rect, start: start, end: (mid - 1))
}
}
}
}
```
更重要的是 `StageLayoutCalculator.swift` 類別。設計此類別的目的是，根據以流程為基礎的資料列/資料欄配置中的參與者人數，來計算每個參與者的影格。每個資料列的高度與其他資料列相同，但每個資料列的寬度可能有所差異。請參閱 `layouts` 變數上方的程式碼註解，描述了如何自訂此行為。
```
import Foundation
import UIKit
class StageLayoutCalculator {
/// This 2D array contains the description of how the grid of participants should be rendered
/// The index of the 1st dimension is the number of participants needed to active that configuration
/// Meaning if there is 1 participant, index 0 will be used. If there are 5 participants, index 4 will be used.
///
/// The 2nd dimension is a description of the layout. The length of the array is the number of rows that
/// will exist, and then each number within that array is the number of columns in each row.
///
/// See the code comments next to each index for concrete examples.
///
/// This can be customized to fit any layout configuration needed.
private let layouts: [[Int]] = [
// 1 participant
[ 1 ], // 1 row, full width
// 2 participants
[ 1, 1 ], // 2 rows, all columns are full width
// 3 participants
[ 1, 2 ], // 2 rows, first row's column is full width then 2nd row's columns are 1/2 width
// 4 participants
[ 2, 2 ], // 2 rows, all columns are 1/2 width
// 5 participants
[ 1, 2, 2 ], // 3 rows, first row's column is full width, 2nd and 3rd row's columns are 1/2 width
// 6 participants
[ 2, 2, 2 ], // 3 rows, all column are 1/2 width
// 7 participants
[ 2, 2, 3 ], // 3 rows, 1st and 2nd row's columns are 1/2 width, 3rd row's columns are 1/3rd width
// 8 participants
[ 2, 3, 3 ],
// 9 participants
[ 3, 3, 3 ],
// 10 participants
[ 2, 3, 2, 3 ],
// 11 participants
[ 2, 3, 3, 3 ],
// 12 participants
[ 3, 3, 3, 3 ],
]
// Given a frame (this could be for a UICollectionView, or a Broadcast Mixer's canvas), calculate the frames for each
// participant, with optional padding.
func calculateFrames(participantCount: Int, width: CGFloat, height: CGFloat, padding: CGFloat) -> [CGRect] {
if participantCount > layouts.count {
fatalError("Only \(layouts.count) participants are supported at this time")
}
if participantCount == 0 {
return []
}
var currentIndex = 0
var lastFrame: CGRect = .zero
// If the height is less than the width, the rows and columns will be flipped.
// Meaning for 6 participants, there will be 2 rows of 3 columns each.
let isVertical = height > width
let halfPadding = padding / 2.0
let layout = layouts[participantCount - 1] // 1 participant is in index 0, so `-1`.
let rowHeight = (isVertical ? height : width) / CGFloat(layout.count)
var frames = [CGRect]()
for row in 0 ..< layout.count {
// layout[row] is the number of columns in a layout
let itemWidth = (isVertical ? width : height) / CGFloat(layout[row])
let segmentFrame = CGRect(x: (isVertical ? 0 : lastFrame.maxX) + halfPadding,
y: (isVertical ? lastFrame.maxY : 0) + halfPadding,
width: (isVertical ? itemWidth : rowHeight) - padding,
height: (isVertical ? rowHeight : itemWidth) - padding)
for column in 0 ..< layout[row] {
var frame = segmentFrame
if isVertical {
frame.origin.x = (itemWidth * CGFloat(column)) + halfPadding
} else {
frame.origin.y = (itemWidth * CGFloat(column)) + halfPadding
}
frames.append(frame)
currentIndex += 1
}
lastFrame = segmentFrame
lastFrame.origin.x += halfPadding
lastFrame.origin.y += halfPadding
}
return frames
}
}
```
回到 `Main.storyboard`，請務必將 `UICollectionView` 的配置類別設定為我們剛才建立的類別：
![\[Xcode interface showing storyboard with UICollectionView and its layout settings.\]](http://docs.aws.amazon.com/zh_tw/ivs/latest/RealTimeUserGuide/images/Publish_iOS_12.png)
## 掛接 UI 動作
我們即將結束，只需建立幾個 `IBActions`。
首先，將處理加入按鈕。其反應因 `connectingOrConnected` 的值而異。一旦建立連線後，便會離開階段。如果中斷連線，則會從權杖 `UITextField` 讀取文字，並建立具有該文字的新的 `IVSStage`。然後，新增 `ViewController` 做為 `strategy`、`errorDelegate` 和用於 `IVSStage` 的轉譯器，最後，我們以非同步方式加入階段。
```
@IBAction private func joinTapped(_ sender: UIButton) {
if connectingOrConnected {
// If we're already connected to a Stage, leave it.
stage?.leave()
} else {
guard let token = textFieldToken.text else {
print("No token")
return
}
// Hide the keyboard after tapping Join
textFieldToken.resignFirstResponder()
do {
// Destroy the old Stage first before creating a new one.
self.stage = nil
let stage = try IVSStage(token: token, strategy: self)
stage.errorDelegate = self
stage.addRenderer(self)
try stage.join()
self.stage = stage
} catch {
print("Failed to join stage - \(error)")
}
}
}
```
需要掛接的另一個 UI 動作是發布切換按鈕：
```
@IBAction private func publishToggled(_ sender: UISwitch) {
// Because the strategy returns the value of `switchPublish.isOn`, just call `refreshStrategy`.
stage?.refreshStrategy()
}
```
## 轉譯參與者
最後，我們需要將從 SDK 接收的資料，轉譯到之前建立的參與者儲存格上。我們已經完成了 `UICollectionView` 邏輯，因此只需實作 `ParticipantCollectionViewCell.swift` 中的 `set` API。
從新增 `empty` 函數開始，然後逐步實作：
```
func set(participant: StageParticipant) {
}
```
首先，處理簡易狀態、參與者 ID、發布狀態和訂閱狀態。對於這些，只需直接更新 `UILabels`：
```
labelParticipantId.text = participant.isLocal ? "You (\(participant.participantId ?? "Disconnected"))" : participant.participantId
labelPublishState.text = participant.publishState.text
labelSubscribeState.text = participant.subscribeState.text
```
發布和訂閱列舉的文字屬性源自本機延伸：
```
extension IVSParticipantPublishState {
var text: String {
switch self {
case .notPublished: return "Not Published"
case .attemptingPublish: return "Attempting to Publish"
case .published: return "Published"
@unknown default: fatalError()
}
}
}
extension IVSParticipantSubscribeState {
var text: String {
switch self {
case .notSubscribed: return "Not Subscribed"
case .attemptingSubscribe: return "Attempting to Subscribe"
case .subscribed: return "Subscribed"
@unknown default: fatalError()
}
}
}
```
接著，更新音訊和影片靜音狀態。為取得靜音狀態，需要從 `streams` 陣列中找到 `IVSImageDevice` 和 `IVSAudioDevice`。為優化效能，會記住上次連接的裝置。
```
// This belongs outside `set(participant:)`
private var registeredStreams: Set = []
private var imageDevice: IVSImageDevice? {
return registeredStreams.lazy.compactMap { $0.device as? IVSImageDevice }.first
}
private var audioDevice: IVSAudioDevice? {
return registeredStreams.lazy.compactMap { $0.device as? IVSAudioDevice }.first
}
// This belongs inside `set(participant:)`
let existingAudioStream = registeredStreams.first { $0.device is IVSAudioDevice }
let existingImageStream = registeredStreams.first { $0.device is IVSImageDevice }
registeredStreams = Set(participant.streams)
let newAudioStream = participant.streams.first { $0.device is IVSAudioDevice }
let newImageStream = participant.streams.first { $0.device is IVSImageDevice }
// `isMuted != false` covers the stream not existing, as well as being muted.
labelVideoMuted.text = "Video Muted: \(newImageStream?.isMuted != false)"
labelAudioMuted.text = "Audio Muted: \(newAudioStream?.isMuted != false)"
```
最後，要轉譯 `imageDevice` 的預覽，並顯示 `audioDevice` 的音訊統計資料:
```
if existingImageStream !== newImageStream {
// The image stream has changed
updatePreview() // We’ll cover this next
}
if existingAudioStream !== newAudioStream {
(existingAudioStream?.device as? IVSAudioDevice)?.setStatsCallback(nil)
audioDevice?.setStatsCallback( { [weak self] stats in
self?.labelAudioVolume.text = String(format: "Audio Level: %.0f dB", stats.rms)
})
// When the audio stream changes, it will take some time to receive new stats. Reset the value temporarily.
self.labelAudioVolume.text = "Audio Level: -100 dB"
}
```
我們需要建立的最後一個函數是 `updatePreview()`，這會將參與者的預覽新增至檢視：
```
private func updatePreview() {
// Remove any old previews from the preview container
viewPreviewContainer.subviews.forEach { $0.removeFromSuperview() }
if let imageDevice = self.imageDevice {
if let preview = try? imageDevice.previewView(with: .fit) {
viewPreviewContainer.addSubviewMatchFrame(preview)
}
}
}
```
上面使用了 `UIView` 上的輔助程式函數，使嵌入子檢視變得更容易：
```
extension UIView {
func addSubviewMatchFrame(_ view: UIView) {
view.translatesAutoresizingMaskIntoConstraints = false
self.addSubview(view)
NSLayoutConstraint.activate([
view.topAnchor.constraint(equalTo: self.topAnchor, constant: 0),
view.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: 0),
view.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 0),
view.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: 0),
])
}
}
```