我有一个在后台播放音频的 iPad 应用程序，但 ipod 控件没有显示应用程序图标

Question

我的问题是 - 当我的 iPad 在后台播放音频时，“我的应用程序图标”不会出现。我正在使用 iPodMusicPlayer。为了在后台播放音频，我编写了这些代码..

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

- (void)viewWillDisappear:(BOOL)animated
{
     [[UIApplication sharedApplication] endReceivingRemoteControlEvents];
     [self resignFirstResponder];
     [super viewWillDisappear:animated];
}

- (BOOL)canBecomeFirstResponder {
        return YES;
}

// iPod 控件将在应用程序处于后台时发送这些事件

- (void) remoteControlReceivedWithEvent: (UIEvent *) receivedEvent {
       if (receivedEvent.type == UIEventTypeRemoteControl) {
           switch (receivedEvent.subtype) {

           case UIEventSubtypeRemoteControlTogglePlayPause:
               [self performSelector:@selector(playPause:)];
               break;

           case UIEventSubtypeRemoteControlPreviousTrack:
            //[self previousSong:nil];
            //[self performSelector:@selector(previousSong:)];
            break;

           case UIEventSubtypeRemoteControlNextTrack:
               //[self performSelector:@selector(nextSong:)];
               break;
          default:
              break;
         }
     }
}

和info.plist我也设置了“必需的后台模式”

Answer 1

您还必须将UIBackgroundModes 添加到您的Info.plist 并将其值设置为audio。

请查看 iOS 应用程序编程指南，特别是 App States and Multitasking section，了解有关如何在后台执行任务的详细信息。

[更新]

还将这两行添加到您的AppDelegate.m 中的application:didFinishLaunchingWithOptions:：

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

当你开始播放音频时，这段代码：

UIBackgroundTaskIdentifier newTaskId = UIBackgroundTaskInvalid;
[_player play];
newTaskId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:NULL];

应该这样做。在模拟器和设备上进行了测试。