画像の一括アップロード-シリアル非同期

- (void) uploadMultiplePicturesWith:(NSArray *) pictures
                           IndexArr:(NSMutableArray *) indexArr      //     ,             
                        completion :(void(^)(BOOL isSuccess)) completion{
    if (!indexArr) {
        indexArr = [NSMutableArray array];
    }
    if ([indexArr count] >= [pictures count]) {
        completion(YES);
        return;
    }
    [self upLoadSigleImage:pictures[indexArr.count] completion:^(BOOL isSuccess) {
        if (isSuccess) {
            [indexArr addObject:@(1)];
            [self uploadMultiplePicturesWith:pictures IndexArr:indexArr completion:completion];
        }else{
            completion(NO);
            return;
        }
    }];
}