后台的

Question

每当我播放一首曲子，然后转到后台，我就无法在我的应用程序中触发这些通知。有人知道为什么或者是怎么回事吗？

        self.player = [MPMusicPlayerController applicationMusicPlayer];
        [self.player beginGeneratingPlaybackNotifications];


        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handlePlaybackStateChanged:) name:MPMusicPlayerControllerPlaybackStateDidChangeNotification object:self.player ];


        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleItemChanged:) name:MPMusicPlayerControllerNowPlayingItemDidChangeNotification object:self.player ];

Answer 1

添加以下代码

UIBackgroundTaskIdentifier bgTask = 0;
UIApplication  *app = [UIApplication sharedApplication];
bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
    [app endBackgroundTask:bgTask];
}];

在AppDelegate的applicationDidEnterBackground方法中，您的方法也将在AppDelegate中工作。

还可以启用

音频、播放和画中画

来自功能。查看屏幕截图

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