目前，我有那段代码:importPhotospublicclassAssetService:NSObject,PHPhotoLibraryChangeObserver{publicoverrideinit(){super.init()PHPhotoLibrary.sharedPhotoLibrary().registerChangeObserver(self)}deinit{PHPhotoLibrary.sharedPhotoLibrary().unregisterChangeObserver(self)}publicfuncphotoLibraryDidChange(changeIn