iOS 保存自定义相册

#pragma mark - 保存图片到自定义相册
- (void)saveImageIntoAlbum
{
    // 获得相片
    PHFetchResult<PHAsset *> *createdAssets = self.createdAssets;
    if (createdAssets == nil) {
        [SVProgressHUD showErrorWithStatus:@"保存图片失败！"];
        return;
    }

    // 获得相册
    PHAssetCollection *createdCollection = self.createdCollection;
    if (createdCollection == nil) {
        [SVProgressHUD showErrorWithStatus:@"创建或者获取相册失败！"];
        return;
    }

    // 添加刚才保存的图片到【自定义相册】
    NSError *error = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:createdCollection];
        [request insertAssets:createdAssets atIndexes:[NSIndexSet indexSetWithIndex:0]];
    } error:&error];

    // 最后的判断
    if (error) {
        [SVProgressHUD showErrorWithStatus:@"保存图片失败！"];
    } else {
        [SVProgressHUD showSuccessWithStatus:@"保存图片成功！"];
    }
}
#pragma mark - 获得当前App对应的自定义相册
- (PHAssetCollection *)createdCollection
{
    // 获得APP名字
    NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString *)kCFBundleNameKey];

    // 抓取所有的自定义相册
    PHFetchResult<PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];

    // 查找当前App对应的自定义相册
    for (PHAssetCollection *collection in collections) {
        if ([collection.localizedTitle isEqualToString:title]) {
            return collection;
        }
    }

    /** 当前App对应的自定义相册没有被创建过 **/
    // 创建一个【自定义相册】
    NSError *error = nil;
    __block NSString *createdCollectionID = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        createdCollectionID = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title].placeholderForCreatedAssetCollection.localIdentifier;
    } error:&error];

    if (error) return nil;

    // 根据唯一标识获得刚才创建的相册
    return [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[createdCollectionID] options:nil].firstObject;
}
#pragma mark - 获得相片
- (PHFetchResult<PHAsset *> *)createdAssets
{
    NSError *error = nil;
    __block NSString *assetID = nil;

    // 保存图片到【相机胶卷】
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        assetID = [PHAssetChangeRequest creationRequestForAssetFromImage:self.imageView.image].placeholderForCreatedAsset.localIdentifier;
    } error:&error];
}