音乐，后台播放，锁屏播放，通知中心播放

第一步 设置：

屏幕快照 2017-07-03 下午7.53.13.png

第二步：Appdelegate

• (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
  }
• (void)applicationWillResignActive:(UIApplication *)application {
  //一般在方法：application: didFinishLaunchingWithOptions:设置
  //获取音频会话
  AVAudioSession *session = [AVAudioSession sharedInstance];
  //设置类型是播放。
  [session setCategory:AVAudioSessionCategoryPlayback error:nil];
  //激活音频会话。
  [session setActive:YES error:nil];
  }

pragma mark - 后台显示播放信息

• (void)setPlayingInfoTotalSeconds:(CGFloat)totalSeconds AndCurrentSecond:(CGFloat)currentSecond AndPlaybackRate:(NSObject *)playbackRate{
  //
  NSIndexPath * selectedIndexPath = [self.tableViewPlain indexPathForSelectedRow];
  RSHomeMusicModel * musicModel = _dataSource[selectedIndexPath.row];
  // 1.获取锁屏中心
  MPNowPlayingInfoCenter *playingInfoCenter = [MPNowPlayingInfoCenter defaultCenter];

  //初始化一个存放音乐信息的字典
  NSMutableDictionary *playingInfoDict = [NSMutableDictionary dictionary];
  // 2、设置歌曲名
  [playingInfoDict setObject:musicModel.musicName forKey:MPMediaItemPropertyAlbumTitle];

  // 设置歌手名
  [playingInfoDict setObject:musicModel.singerName forKey:MPMediaItemPropertyArtist];

  // 3设置封面的图片
  // UIImage *image = [self getMusicImageWithMusicId:self.currentModel];
  // if (image) {
  MPMediaItemArtwork *artwork = [[MPMediaItemArtwork alloc] initWithImage:[UIImage imageNamed:@"l6_1_home_img_01"]];
  [playingInfoDict setObject:artwork forKey:MPMediaItemPropertyArtwork];

  // 4设置歌曲的总时长
  [playingInfoDict setObject:@(totalSeconds) forKey:MPMediaItemPropertyPlaybackDuration];
  // 当前播放时间
  [playingInfoDict setObject:@(currentSecond) forKey:MPNowPlayingInfoPropertyElapsedPlaybackTime];
  //速度
  [playingInfoDict setObject:playbackRate forKey:MPNowPlayingInfoPropertyPlaybackRate];

  //音乐信息赋值给获取锁屏中心的nowPlayingInfo属性
  playingInfoCenter.nowPlayingInfo = playingInfoDict;

  // 5.开启远程交互，只有开启这个才能进行远程操控
  [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

}

//监听远程交互方法

• (void)remoteControlReceivedWithEvent:(UIEvent *)event
  {
  switch (event.subtype) {
  //播放
  case UIEventSubtypeRemoteControlPlay:{

        NSIndexPath * selectedIndexPath = [self.tableViewPlain indexPathForSelectedRow];
        RSHomeMusicModel * musicModel = _dataSource[selectedIndexPath.row];
  
        [self setPlayingInfoTotalSeconds:musicModel.totalSeconds  AndCurrentSecond:musicModel.currentSecond AndPlaybackRate:@(1)];
  
            [_audioTool jk_play];
    }
        break;
        //停止
    case UIEventSubtypeRemoteControlPause:{
    
        NSIndexPath * selectedIndexPath = [self.tableViewPlain indexPathForSelectedRow];
        RSHomeMusicModel * musicModel = _dataSource[selectedIndexPath.row];
  
        [self setPlayingInfoTotalSeconds:musicModel.totalSeconds  AndCurrentSecond:musicModel.currentSecond AndPlaybackRate:@(0)];
        NSLog(@"当前模型播放时间 : %f",musicModel.totalSeconds);
        _playButton.selected = NO;
        [_audioTool jk_pause];
        
    }
        break;
        //下一首
    case UIEventSubtypeRemoteControlNextTrack:
        [self nextButtonClick];
        
        break;
        //上一首
    case UIEventSubtypeRemoteControlPreviousTrack:
        [self previousButtonClick];
        
        break;
        
    default:
        break;
  

  }
  }