AVAudioPlayer的锁屏播放控制和锁屏播放信息显示

在设置这个锁屏之前，首先得设置应用支持后台音乐播放，TAGETS->Info->Required background modes->App plays audio or streams audio/video using AirPlay

或者在plist中设置如上边数据。

1.添加self为第一响应者，并设置接收远程控制

    [self becomeFirstResponder];
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

-(BOOL)becomeFirstResponder{
    return YES;
}

2.利用data初始化音乐播放器AVAudioPlayer，并设置prepareToPlay。

self.AudioPlayer = [[AVAudioPlayer alloc]initWithData:data error:&error];
[self.AudioPlayer prepareToPlay];

3.在播放/暂停的按钮控制中，设置音乐锁屏信息，一般每次播放和暂停的时候刷新锁屏信息

- (IBAction)clickbtn:(id)sender {
    UIButton *btn = sender;
    if (btn.tag == ) {
        [self.AudioPlayer play];

    }else{
        [self.AudioPlayer pause];
    }
    btn.tag *= -;
    if (self.AudioPlayer.isPlaying) {
        NSLog(@"yes");
    }else{
        NSLog(@"no");
    }

    NSMutableDictionary *songInfo = [ [NSMutableDictionary alloc] init];
    //锁屏图片
    UIImage *img = [UIImage imageNamed:@"logo152"];
    if (img) {
        MPMediaItemArtwork *albumArt = [[MPMediaItemArtwork alloc]initWithImage:img];
        [songInfo setObject: albumArt forKey:MPMediaItemPropertyArtwork ];
    }
    //锁屏标题
    NSString *title = @"music";
    [songInfo setObject:[NSNumber numberWithFloat:] forKey:MPMediaItemPropertyPlaybackDuration];
    [songInfo setObject:title forKey:MPMediaItemPropertyTitle];
    [songInfo setObject:title forKey:MPMediaItemPropertyAlbumTitle];
    [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:songInfo ];

}

4.添加接收远程控制的方法

- (void)remoteControlReceivedWithEvent:(UIEvent *)event
{
    switch (event.subtype)
    {
        case UIEventSubtypeRemoteControlPlay:
            NSLog(@"%s-%d",__FUNCTION__,__LINE__);
            //play
            [self.AudioPlayer play];
            break;
        case UIEventSubtypeRemoteControlPause:
//            NSLog(@"%s-%d",__FUNCTION__,__LINE__);
            //pause
            [self.AudioPlayer pause];
            break;
        case UIEventSubtypeRemoteControlStop:
            NSLog(@"%s-%d",__FUNCTION__,__LINE__);
            //stop
            break;
        default:
            break;
    }
}