QuickBlox：如何使用quickblox sdk 1.9在ios中下载图像文件和视频文件

Question

我将quickblox sdk 1.9与ios集成，用于文件下载和使用此代码

NSString *name =[[[SSCContentManager instance] lastObjectFromFileList] name];
NSString *fileID = [[[SSCContentManager instance] lastObjectFromFileList] UID];
if (fileID > 0) {
    // Download file from QuickBlox server

    [QBRequest downloadFileWithUID:fileID successBlock:^(QBResponse *response, NSData *fileData) {
        if ( fileData ) {

            // Add image to gallery
            [[SSCContentManager instance] savePicture:[UIImage imageWithData: fileData]];
            UIImageView* imageView = [[UIImageView alloc] initWithImage:[UIImage imageWithData:fileData]];
            imageView.contentMode = UIViewContentModeScaleAspectFit;
            [self showImage:imageView];
            //
            [[SSCContentManager instance] removeLastObjectFromFileList];

            // Download next file
            [self downloadFile];
        } else {
            [[SSCContentManager instance] removeLastObjectFromFileList];

            // download next file
            [self downloadFile];
        }
    } statusBlock:^(QBRequest *request, QBRequestStatus *status) {
        NSLog(@"progress for %@: %f", name, status.percentOfCompletion);
    }  errorBlock:^(QBResponse *response) {
        NSLog(@"%@", response.error.error);
        [[SSCContentManager instance] removeLastObjectFromFileList];

        // download next file
        [self downloadFile];
    }];
}

然后它给出错误QBRequest，找不到或未声明文件数据但是在使用此代码上传文件时

[QBContent TUploadFile:imageData fileName:imageName contentType:@"image/png" isPublic:NO delegate:self];

然后成功上传文件。下载文件有什么问题以及解决方法？