How download a image since QuickBox API?

i'm trying download a image file since Quickblox API. I can upload a file, but when i tried download NSData image doesn't show a image.

// Upload a user avatar, previously log in Quickblox API
                NSData *avatar = UIImagePNGRepresentation([UIImage imageNamed:@"userWhite"]);
                [QBRequest TUploadFile:avatar fileName:@"avatar.png" contentType:@"image/png" isPublic:YES successBlock:^(QBResponse *response, QBCBlob *blob) {
                    // Success
                } statusBlock:^(QBRequest *request, QBRequestStatus *status) {

                } errorBlock:^(QBResponse *response) {

                }];

Image Upload: Image

Download avatar:

 NSString* userProfilePictureID = [NSString stringWithFormat:@"%ld",(long)[[LocalStorageService shared] currentUser].blobID]; // user - an instance of QBUUser class
    // download user profile picture
    [QBRequest downloadFileWithUID:@"318547" successBlock:^(QBResponse *response, NSData *fileData) { UIImage* image = [UIImage imageWithData:fileData];

    } statusBlock:^(QBRequest *request, QBRequestStatus *status) {

    } errorBlock:^(QBResponse *response) {
    }];

UIImage doesn't show any image. What do?, NSData isn't corrupted. Thanks.