iCloud upload progress objective c

Question

Is there any way to know the status of the file uploading to iCloud? Here the code that I used to upload:

 FileDocument *doc = [[FileDocument alloc] initWithFileURL:des];
    doc.data = [NSData dataWithContentsOfURL:src];
    [doc saveToURL:des forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
        if (success) {
            NSLog(@"Success");
        } else {
            NSLog(@"Fail");
        }
    }];

I've searched for it but cannot find the answer.