我正在尝试了解如何正确检测播放器项目何时可以再次播放。查看下面的观察者逻辑:if(object==playerItem&&[keyPathisEqualToString:@"playbackBufferEmpty"]){if(playerItem.playbackBufferEmpty){//showloadingindicator}}if(object==playerItem&&[keyPathisEqualToString:@"playbackLikelyToKeepUp"]){if(playerItem.playbackLikelyToKeepUp){//hideloadingi