1.在TARGETS -->Capabilities–>Background Modes开启并勾选Audio,AirPlay,and Picture

2.在- (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions中写入以下代码:

NSError *setCategoryErr = nil;

NSError *activationErr  = nil;

[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&setCategoryErr];

[[AVAudioSession sharedInstance] setActive:YES error:&activationErr];

3.在- (void)applicationDidEnterBackground:(UIApplication*)application中写入以下代码:

UIApplication *app = [UIApplication sharedApplication];

__block UIBackgroundTaskIdentifier bgTask;

bgTask = [appbeginBackgroundTaskWithExpirationHandler:^{

    dispatch_async(dispatch_get_main_queue(), ^{

        if(bgTask != UIBackgroundTaskInvalid)
        {

            bgTask = UIBackgroundTaskInvalid;
        }
    });
}];

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    dispatch_async(dispatch_get_main_queue(), ^{

        if(bgTask != UIBackgroundTaskInvalid)
        {
            bgTask = UIBackgroundTaskInvalid;
        }
    });
});