锁屏iPod控件无法使用Spotify音乐播放器

Question

我将Spotify播放器添加到我的应用程序中,该应用程序也使用MPMusicPlayerController播放音乐.当Spotify播放音乐并且屏幕被锁定时,当用户按下锁定屏幕上的这些按钮时,不会收到播放/暂停和FFW/RWD的遥控事件.

如果从MPMusicPlayerController播放音乐,我可以根据以下代码接收远程控制事件:

-(void) ViewDidLoad {
    ...
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
    [self becomeFirstResponder];
    ...
}

和

- (BOOL) canBecomeFirstResponder
{
    return YES;
}

- (void) remoteControlReceivedWithEvent: (UIEvent*) event
{
    // see [event subtype] for details
    if (event.type == UIEventTypeRemoteControl) {
        // We may be receiving an event from the lockscreen
        switch (event.subtype) {
            case UIEventSubtypeRemoteControlTogglePlayPause:
            case UIEventSubtypeRemoteControlPlay:
            case UIEventSubtypeRemoteControlPause:
                // User pressed play or pause from lockscreen
                [self playOrPauseMusic:nil];
                break;

            case UIEventSubtypeRemoteControlNextTrack:
                // User pressed FFW from lockscreen
                [self fastForwardMusic:nil];
                break;

            case UIEventSubtypeRemoteControlPreviousTrack:
                // User pressed rewind from lockscreen
                [self rewindMusic:nil];
                break;

            default:
                break;
        }
    }
}

当应用程序进入后台时,iPod控件可见,但当我按暂停时,它们不会响应.相反,当我按下暂停时iPod控制消失.当从锁定屏幕在后台播放Spotify等流式传输音频时,需要增加什么才能检测播放/暂停和FFW/RWD？

Answer 1

经过进一步调查，我发现如果在我的应用程序进入后台和接收到远程控制事件时包含以下代码，iPod 控件不会消失。

// Set up info center to display album artwork within ipod controls (needed for spotify)
MPMediaItemArtwork *ipodControlArtwork = [[MPMediaItemArtwork alloc]initWithImage:artworkImage];
[MPNowPlayingInfoCenter defaultCenter].nowPlayingInfo = [NSDictionary dictionaryWithObjectsAndKeys:nowPlayingTitle, MPMediaItemPropertyTitle,
                                                         nowPlayingArtist, MPMediaItemPropertyArtist, ipodControlArtwork, MPMediaItemPropertyArtwork,  [NSNumber numberWithDouble:0.0], MPNowPlayingInfoPropertyPlaybackRate, nil];