ios 音乐后台播放

 NSString *musicPath = [[NSBundle mainBundle] pathForResource:@"净土"
                                                          ofType:@"mp3"];
    if (musicPath) 
    {
        NSURL *musicURL = [NSURL fileURLWithPath:musicPath];
        [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
        audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:musicURL  error:nil];
        [audioPlayer setDelegate:self];
    }