播放后台音频

@property (nonatomic, strong) AVAudioSession *session;

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.session = [AVAudioSession sharedInstance];
    NSError *error;
    //申明后台模式播放
    [self.session setCategory:AVAudioSessionCategoryPlayback error:&error];
    if (error)
    {
        NSLog(@"Error setting audio session category: %@", error);
    }
    [self.session setActive:YES error:&error];
    if (error)
    {
        NSLog(@"Error activating audio session: %@", error);
    }
}

//使用户能够远程控制媒体播放器，通过耳机或者活动栏。
-(BOOL)canBecomeFirstResponder
{
    return YES;
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    //注册远程控制事件
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
    [self becomeFirstResponder];
}

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

//接收和响应远程控制事件
- (void)remoteControlReceivedWithEvent: (UIEvent *) receivedEvent
{
    if (receivedEvent.type == UIEventTypeRemoteControl)
    {
        switch (receivedEvent.subtype)
        {
            //调用各自的动作方法实现事件的定向
            case UIEventSubtypeRemoteControlTogglePlayPause:
                [self togglePlay:self];
                break;
                
            case UIEventSubtypeRemoteControlPreviousTrack:
                [self goToPrevTrack:self];
                break;
                
            case UIEventSubtypeRemoteControlNextTrack:
                [self goToNextTrack:self];
                break;
                
            default:
                break;
        }
    }
}

@property (nonatomic, strong) AVPlayer *player;
@property (nonatomic, strong) NSMutableArray *playlist;
@property (nonatomic)NSInteger currentIndex;

- (void)viewDidLoad
{
    [super viewDidLoad];

        .
        .
        .
    
    self.playlist = [[NSMutableArray alloc] init];
    self.player = [[AVPlayer alloc] init];
}