如果服务器上没有文件(或另一个服务器错误)AVPlayer会返回错误5-10秒。如何设置超时？示例:letassetKeys=["playable","tracks","duration"]asset.loadValuesAsynchronouslyForKeys(assetKeys){varloaded=falseforassetKeyinassetKeys{varerror:NSError?letstatus=asset.statusOfValueForKey(assetKey,error:&error)loaded=status==.Loaded}if!loaded{//erro