iOS音乐后台播放及锁屏信息显示

#import <AVFoundation/AVFoundation.h>
#import <MediaPlayer/MediaPlayer.h>

- (void)viewDidLoad {
  [super viewDidLoad];
//  设置后台播放
  [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];

//  设置播放器
  NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"那些花儿" ofType:@"mp3"] ];
  _player = [[AVPlayer alloc] initWithURL:url];
  [_player play];
  _isPlayingNow = YES;

  //后台播放显示信息设置
  [self setPlayingInfo];
}

#pragma mark - 接收方法的设置
- (void)remoteControlReceivedWithEvent:(UIEvent *)event {
  if (event.type == UIEventTypeRemoteControl) { //判断是否为远程控制
    switch (event.subtype) {
      case UIEventSubtypeRemoteControlPlay:
        if (!_isPlayingNow) {
          [_player play];
        }
        _isPlayingNow = !_isPlayingNow;
        break;
      case UIEventSubtypeRemoteControlPause:
        if (_isPlayingNow) {
          [_player pause];
        }
        _isPlayingNow = !_isPlayingNow;
        break;
      case UIEventSubtypeRemoteControlNextTrack:
        NSLog(@"下一首");
        break;
      case UIEventSubtypeRemoteControlPreviousTrack:
        NSLog(@"上一首 ");
        break;
      default:
        break;
    }
  }
}

- (void)setPlayingInfo {
//  <MediaPlayer/MediaPlayer.h>
  MPMediaItemArtwork *artWork = [[MPMediaItemArtwork alloc] initWithImage:[UIImage imageNamed:@"pushu.jpg"]];

  NSDictionary *dic = @{MPMediaItemPropertyTitle:@"那些花儿",
             MPMediaItemPropertyArtist:@"朴树",
             MPMediaItemPropertyArtwork:artWork
             };
  [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:dic];
}

- (void)viewDidAppear:(BOOL)animated {
//  接受远程控制
  [self becomeFirstResponder];
  [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
}

- (void)viewDidDisappear:(BOOL)animated {
//  取消远程控制
  [self resignFirstResponder];
  [[UIApplication sharedApplication] endReceivingRemoteControlEvents];
}