iphone - MPMoviePlayerViewController 在后台运行并使用远程控制

Question

我目前在 iOS 4.3.5 上运行，并尝试让我的 MPMoviePlayerViewController 在进入后台后继续播放。

我按照上面的描述实现了所有内容

http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html

和

http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/RemoteControl/RemoteControl.html

我还将 UIBackgroundMode 设置为音频。

我的自定义 MPMoviePlayerViewController 类是从 TabBarApplication 中这样调用的:

    NSURL *streamUrl = [NSURL URLWithString:STREAM_URL];

self.playerViewController = [[CustomMoviePlayerViewController alloc] initWithContentURL:streamUrl];

// Register for the playback finished notification
[[NSNotificationCenter defaultCenter] addObserver:self
                                            selector:@selector(myMovieFinishedCallback:)
                                            name:MPMoviePlayerPlaybackDidFinishNotification
                                            object:self.playerViewController.moviePlayer];
// Present
[self presentMoviePlayerViewControllerAnimated:self.playerViewController];

// Play the movie!
self.playerViewController.moviePlayer.movieSourceType = MPMovieSourceTypeStreaming;
[self.playerViewController.moviePlayer prepareToPlay];
[self.playerViewController.moviePlayer play];

我的CustomMovePlayerController内部如下所示:

-(void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
}

-(void)viewWillAppear:(BOOL)animated {
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[self becomeFirstResponder];
}

-(void)viewWillDisappear:(BOOL)animated {
[[UIApplication sharedApplication] endReceivingRemoteControlEvents];

[self resignFirstResponder];
[super viewWillDisappear:animated];
}

-(BOOL)canBecomeFirstResponder {
return YES;
}

-(void)remoteControlReceivedWithEvent:(UIEvent *)event {
[super remoteControlReceivedWithEvent:event];
NSLog(@"remoteControlReceived");
NSLog(@"%d", [[AVAudioSession sharedInstance] isActive]);
if (event.type == UIEventTypeRemoteControl) {
    switch (event.subtype) {
        case UIEventSubtypeRemoteControlPlay:
            [self.moviePlayer play];
            break;

        case UIEventSubtypeRemoteControlPause:
            [self.moviePlayer pause];
            break;          
        default:
            break;
    }
}
}

我的 MPMoviePlayerViewController 的主要问题是，它不响应 remoteControlReceivedWithEvent 消息，这是为什么？我是否子类化了错误的东西？我的基于选项卡栏的应用程序是否会阻止我这样做？

最后但并非最不重要的 - applicationDidFinishLaunchingWithOptions 包含以下内容:

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
[audioSession setCategory:AVAudioSessionCategoryPlayback error:nil];
[audioSession setActive:YES error:nil];

我只是不知道缺少了什么...非常感谢所有帮助!

Answer 1

我想我可以回答这两个问题:)

背景问题:

您想播放什么格式的文件？我的应用程序使用 MPMoviePlayerViewController 作为背景音频已有一段时间了，但最近有报告称它不再在后台播放。

原来是AAC文件；它们是带有章节和每章封面艺术的播客... iOS 5 添加了对它们的改进支持，但它必须使 MPMoviePlayerViewController 认为它正在播放视频。据我所知，iOS 4.3 左右背景视频被关闭。

尝试使用普通 MP3 文件，它仍然适用于我。我即将将 AAC 问题记录为 Apple 的错误。

远程控制问题:

锁屏和通知栏遥控按钮都会发送UIEventSubtypeRemoteControlTogglePlayPause事件，而不是单独播放和暂停。所以我处理这样的事件:

- (void)remoteControlReceivedWithEvent:(UIEvent *)event {
  switch (event.subtype) {
    case UIEventSubtypeRemoteControlTogglePlayPause:
      if (controller.playbackState == MPMusicPlaybackStatePlaying) {
          [controller pause];
      } else {
          [controller play];
      }
      break;
     //etc
}