為您的 iOS 應用程式新增進階功能

廣告插播

iOS 傳送端 SDK 支援指定媒體串流中的廣告插播和隨播廣告。

如要進一步瞭解廣告插播的運作方式，請參閱「Web 接收端廣告插播總覽」。

雖然傳送端和接收端都可以指定廣告插播，但建議在網路接收端和 Android TV 接收端指定，以維持跨平台的一致行為。

在 iOS 上，使用 GCKAdBreakClipInfo 和 GCKAdBreakInfo 在載入指令中指定廣告插播：

Swift
let breakClip1Builder = GCKAdBreakClipInfoBuilder(adBreakClipID: "bc0")
breakClip1Builder.title = "Clip title"
if let posterUrl = URL(string: "https://www.some.url") {
  breakClip1Builder.posterURL = posterUrl
}
breakClip1Builder.duration = 60
breakClip1Builder.whenSkippable = 5  // Set this field so that the ad is skippable
let breakClip1 = breakClip1Builder.build()

let breakClip2 = ...
let breakClip3 = ...


let break1 = GCKAdBreakInfoBuilder(adBreakID: "b0", adBreakClipIds: ["bc0", "bc1", "bc2"]).build()
let mediaInfoBuilder = GCKMediaInformationBuilder(entity: "entity")
...
mediaInfoBuilder.adBreaks = [break1]
mediaInfoBuilder.adBreakClips = [breakClip1, breakClip2, breakClip3]
...
mediaInformation = mediaInfoBuilder.build()

let mediaLoadRequestDataBuilder = GCKMediaLoadRequestDataBuilder()
mediaLoadRequestDataBuilder.mediaInformation = mediaInformation

sessionManager.currentSession?.remoteMediaClient?.loadMedia(with: mediaLoadRequestDataBuilder.build())
Objective-C
GCKAdBreakClipInfoBuilder *breakClipInfoBuilder = [[GCKAdBreakClipInfoBuilder alloc] initWithAdBreakClipID:@"bc0"];
breakClipInfoBuilder.title = @"Clip title";
breakClipInfoBuilder.posterURL = [[NSURL alloc] initWithString:@"https://www.some.url"];
breakClipInfoBuilder.duration = 60;
breakClipInfoBuilder.whenSkippable = 5;
GCKAdBreakClipInfo *breakClip1 = breakClipInfoBuilder.build;

GCKAdBreakClipInfo *breakClip2 = ...
GCKAdBreakClipInfo *breakClip3 = ...

GCKAdBreakInfo *break1 = [[GCKAdBreakInfoBuilder alloc] initWithAdBreakID:@"b0"
                                                           adBreakClipIds:@[@"bc0", @"bc1", @"bc2"]].build;

GCKMediaInformationBuilder *mediaInfoBuilder = [[GCKMediaInformationBuilder alloc]
                                                initWithEntity:@"entity"];
...
mediaInfoBuilder.adBreaks = @[break1];
mediaInfoBuilder.adBreakClips = @[breakClip1, breakClip2, breakClip3];
...
self.mediaInformation = [mediaInfoBuilder build];

GCKMediaLoadRequestDataBuilder *mediaLoadRequestDataBuilder = [[GCKMediaLoadRequestDataBuilder alloc] init];
mediaLoadRequestDataBuilder.mediaInformation = self.mediaInformation;

// Send a load request to the remote media client.
GCKRequest *request = [self.sessionManager.currentSession.remoteMediaClient
                                loadMediaWithLoadRequestData:[mediaLoadRequestDataBuilder build]];

可變播放速率

應用程式可以顯示及變更目前媒體項目的播放速率。您可以使用 GCKRemoteMediaClient 的 -[setPlaybackRate:] 或 -[setPlaybackRate:customData:] 設定速率，使用 GCKUIMediaController 的 playbackRateController 存取 GCKUIPlaybackRateController，並使用 GCKUIPlaybackRateController 的 playbackRate 顯示目前的播放速率。

程式碼範例

以下兩個檔案會實作 GCKUIPlaybackRateController，使用具有「一般」、「半速」和「雙倍速」按鈕的分段控制項，控制播放速率：

Swift
import GoogleCast

/**
 * An implementation of GCKUIPlaybackRateController that controls playback rate
 * using a segmented control that has "normal", "half speed", and "double speed"
 * buttons.
 */
class SegmentedButtonPlaybackRateController: GCKUIPlaybackRateController {
  static let kSegmentNormal = 0;
  static let kSegmentHalfSpeed = 1;
  static let kSegmentDoubleSpeed = 2;

  var segmentedControl: UISegmentedControl!

  override var playbackRate: Float {
    didSet {
      var buttonIndex = 0

      // Map the playback rate to one of our three supported speeds.
      if playbackRate == 1.0 {
        buttonIndex = SegmentedButtonPlaybackRateController.kSegmentNormal
      } else if playbackRate < 1.0 {
        buttonIndex = SegmentedButtonPlaybackRateController.kSegmentHalfSpeed
      } else {
        buttonIndex = SegmentedButtonPlaybackRateController.kSegmentDoubleSpeed
      }

      segmentedControl?.selectedSegmentIndex = buttonIndex
    }
  }
  override var inputEnabled: Bool {
    didSet {
      segmentedControl?.isEnabled = inputEnabled
    }
  }

  /**
   * Designated initializer.
   *
   * @param segmentedControl The segmented control for changing/displaying the
   * playback rate.
   */
  convenience init(_ segmentedControl: UISegmentedControl) {
    self.init()
    self.segmentedControl = segmentedControl;

    segmentedControl.addTarget(self,
                               action: #selector(segmentedControlTapped(sender:)),
                               for: UIControl.Event.valueChanged)
  }

  @objc func segmentedControlTapped(sender: UISegmentedControl) {
    var playbackRate: Float = 1.0

    switch segmentedControl?.selectedSegmentIndex {
    case SegmentedButtonPlaybackRateController.kSegmentHalfSpeed:
      playbackRate = 0.5;
    case SegmentedButtonPlaybackRateController.kSegmentDoubleSpeed:
      playbackRate = 2.0;
    case SegmentedButtonPlaybackRateController.kSegmentNormal:
      fallthrough
    default:
      playbackRate = 1.0;
    }

    self.playbackRate = playbackRate
  }
}
Objective-C

SegmentedButtonPlaybackRateController.h

#import <GoogleCast/GoogleCast.h>
#import <UIKit/UIKit.h>

/**
 * An implementation of GCKUIPlaybackRateController that controls playback rate
 * using a segmented control that has "normal", "half speed", and "double speed"
 * buttons.
 */
@interface SegmentedButtonPlaybackRateController : GCKUIPlaybackRateController

/**
 * Designated initializer.
 *
 * @param segmentedControl The segmented control for changing/displaying the
 * playback rate.
 */
- (instancetype)initWithSegmentedControl:(UISegmentedControl *)segmentedControl;

@end

SegmentedButtonPlaybackRateController.m

#import "SegmentedButtonPlaybackRateController.h"

@interface SegmentedButtonPlaybackRateController () {
  UISegmentedControl *_segmentedControl;
}

@end

static const NSInteger kSegmentNormal = 0;
static const NSInteger kSegmentHalfSpeed = 1;
static const NSInteger kSegmentDoubleSpeed = 2;

@implementation SegmentedButtonPlaybackRateController

- (instancetype)initWithSegmentedControl:(UISegmentedControl *)segmentedControl {
  if (self = [super init]) {
    _segmentedControl = segmentedControl;
    [_segmentedControl addTarget:self
                          action:@selector(segmentedControlTapped:)
                forControlEvents:UIControlEventValueChanged];
  }
  return self;
}

- (void)setPlaybackRate:(float)playbackRate {
  [super setPlaybackRate:playbackRate];

  NSInteger buttonIndex = 0;

  // Map the playback rate to one of our three supported speeds.
  if (playbackRate == 1.0) {
    buttonIndex = kSegmentNormal;
  } else if (playbackRate < 1.0) {
    buttonIndex = kSegmentHalfSpeed;
  } else {
    buttonIndex = kSegmentDoubleSpeed;
  }

  _segmentedControl.selectedSegmentIndex = buttonIndex;
}

- (void)setInputEnabled:(BOOL)inputEnabled {
  _segmentedControl.enabled = inputEnabled;
  [super setInputEnabled:inputEnabled];
}

- (void)segmentedControlTapped:(id)sender {
  float playbackRate;

  switch (_segmentedControl.selectedSegmentIndex) {
    case kSegmentHalfSpeed:
      playbackRate = 0.5;
      break;

    case kSegmentDoubleSpeed:
      playbackRate = 2.0;
      break;

    case kSegmentNormal:
    default:
      playbackRate = 1.0;
      break;
  }

  self.playbackRate = playbackRate;
}

@end

新增自訂管道

Cast 架構提供兩種建立管道的方法，可將自訂訊息傳送至 Web 接收端：

  1. GCKCastChannel 應設為子類別，以實作具有相關聯狀態的重要管道。
  2. GCKGenericChannel 是子類別的替代方案，會將收到的訊息傳遞給委派，以便在其他地方處理。

以下是 GCKCastChannel 導入範例：

Swift
class HGCTextChannel: GCKCastChannel {
  override func didReceiveTextMessage(_ message: String) {
    print("received message: \(message)")
  }
}
Objective-C

HGCTextChannel.h

#import <GoogleCast/GCKCastChannel.h>

@interface HGCTextChannel : GCKCastChannel

@end

HGCTextChannel.m

#import "HGCTextChannel.h"

@implementation HGCTextChannel
- (void)didReceiveTextMessage:(NSString*)message {
  NSLog(@"received message: %@", message);
}

@end

頻道隨時可以註冊；如果工作階段目前未處於連線狀態，只要頻道命名空間存在於 Web 接收器應用程式中繼資料的支援命名空間清單中，頻道就會在工作階段連線時自動連線。

每個自訂管道都由不重複的命名空間定義，且必須以前置字串 urn:x-cast: 開頭，例如 urn:x-cast:com.example.custom。您可以建立多個自訂管道，每個管道都有專屬的命名空間。Web 接收端應用程式也可以使用相同的命名空間傳送及接收訊息。

Swift
var error: GCKError?
let textChannel = HGCTextChannel.init(namespace: "urn:x-cast:com.google.cast.sample.helloworld")
sessionManager.currentCastSession?.add(textChannel)
textChannel.sendTextMessage("Hello World", error: &error)

if error != nil {
  print("Error sending text message \(error.debugDescription)")
}
Objective-C
NSError *error;
HGCTextChannel *textChannel = [[HGCTextChannel alloc] initWithNamespace:@"urn:x-cast:com.google.cast.sample.helloworld"];
[sessionManager.currentCastSession addChannel:textChannel];
[textChannel sendTextMessage:@"Hello World"
                       error:&error];

if (error != nil) {
  NSLog(@"Error sending text message: %@", error);
}

如要提供在特定管道連線或中斷連線時執行的邏輯，請覆寫 -[didConnect] 和 -[didDisconnect] 方法 (如果使用 GCKCastChannel)，或提供 GCKGenericChannelDelegate 的 -[castChannelDidConnect:] 和 -[castChannelDidDisconnect:] 方法實作 (如果使用 GCKGenericChannel)。

支援自動播放

請參閱自動播放和佇列 API。

覆寫圖片選取和快取

架構的各個元件 (即投放對話方塊、迷你控制器、展開式控制器，以及 GCKUIMediaController (如有設定)) 會顯示目前投放媒體的圖片。圖片作品的網址通常包含在媒體的 GCKMediaMetadata 中，但傳送端應用程式可能有其他網址來源。

GCKUIImagePicker 通訊協定定義了根據指定用途和所需大小選取適當圖片的方法。這個介面只有一個方法 -[getImageWithHints:fromMetadata:]，會採用 GCKUIImageHints 物件和 GCKMediaMetadata 物件做為參數，並傳回 GCKImage 物件做為結果。架構提供 GCKUIImagePicker 的預設實作，一律會選取 GCKMediaMetadata 物件圖片清單中的第一張圖片，但應用程式可以透過設定 GCKCastContext 單例模式的 imagePicker 屬性，提供替代實作。

GCKUIImageCache 通訊協定也定義了快取架構使用 HTTPS 下載的圖片的方法。架構提供 GCKUIImageCache 的預設實作，可將下載的圖片檔儲存在應用程式的快取目錄中，但應用程式可以透過設定 GCKCastContext 單例模式的 imageCache 屬性，提供替代實作。

後續步驟

以上就是可新增至 iOS 傳送端應用程式的功能。您現在可以建構其他平台的傳送端應用程式 (Android 或網頁)，或建構網頁接收端。

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