关于ios9中得ALAssetsLibrary框架过时问题

用Photos框架代替。

其中：保存视频的代码：

        ALAssetsLibrary *assetsLibrary=[[ALAssetsLibrary alloc]init];

        [assetsLibrary writeVideoAtPathToSavedPhotosAlbum:mediaUrl completionBlock:^(NSURL *assetURL, NSError *error) {

            if (!error) {

                NSLog(@"视频保存成功");

            }

            else

            {

                NSLog(@"视频保存失败");

            }

        }];

ios9中得代码：(不确定正确性)

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{

            // Request creating an asset from the image.

            PHAssetChangeRequest *createAssetRequest = [PHAssetChangeRequest creationRequestForAssetFromVideoAtFileURL:mediaUrl];

            PHFetchResult *result=[PHAsset fetchAssetsWithALAssetURLs:[NSArray arrayWithObject:mediaUrl] options:nil];

            

            PHAssetCollection *assetColection=[[PHAssetCollection fetchAssetCollectionsContainingAsset:[result lastObject] withType:PHAssetCollectionTypeAlbum options:nil] lastObject];

            // Request editing the album.

            PHAssetCollectionChangeRequest *albumChangeRequest = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:assetColection];

            

            // Get a placeholder for the new asset and add it to the album editing request.

            PHObjectPlaceholder *assetPlaceholder = [createAssetRequest placeholderForCreatedAsset];

            [albumChangeRequest addAssets:@[ assetPlaceholder ]];

            

        } completionHandler:^(BOOL success, NSError *error) {

            NSLog(@"Finished adding asset. %@", (success ? @"Success" : error));

        }];