Ios 为什么播放音乐时，锁屏和指挥中心上的控制按钮会禁用？

播放音乐时，为什么要禁用锁屏和命令中心上的控制按钮？我使用MPRemoteCommandCenter通过远程控制访问。非常感谢你的帮助

顺便说一句

应用程序没有被杀死

我添加admob SDK作为我的应用程序插入广告

    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.1) {
    MPRemoteCommandCenter *commandCenter = [MPRemoteCommandCenter sharedCommandCenter];
    commandCenter.playCommand.enabled = YES;
    [commandCenter.playCommand addTarget:self action:@selector(playAction:)];

    [commandCenter.pauseCommand addTarget:self action:@selector(pauseAction:)];

    commandCenter.previousTrackCommand.enabled = YES;
    [commandCenter.previousTrackCommand addTarget:self action:@selector(previousTrackAction:)];

    commandCenter.nextTrackCommand.enabled = YES;
    [commandCenter.nextTrackCommand addTarget:self action:@selector(nextTrackAction:)];

    commandCenter.togglePlayPauseCommand.enabled = YES;
    [commandCenter.togglePlayPauseCommand addTarget:self action:@selector(playOrPauseAction:)];
}