MBProgressHUD Hiding indicator after GCD - ios

Question

The user is able to click a button to download a set of maps, upon completion of that task, I would like to hide the progress indicator. I have tried several variants of the below code but have not achieved what I am searching for. Any guidance would be appreciated.
- (IBAction)SavePhotoOnClick:(id)sender{
HUD = [[MBProgressHUD alloc] initWithView:self.navigationController.view];
[self.navigationController.view addSubview:HUD];
dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
NSURL *url = [NSURL URLWithString:urlstr1];
UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil); dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
});
// Set determinate mode
HUD.mode = MBProgressHUDModeDeterminate;
HUD.dimBackground = YES;
HUD.color = [UIColor colorWithRed:0.23 green:0.50 blue:0.82 alpha:0.90];
HUD.delegate = self;
HUD.labelText = #"Downloading Maps";
// myProgressTask uses the HUD instance to update progress
[HUD showWhileExecuting:#selector(myProgressTask) onTarget:self withObject:nil animated:YES];
}
- (void)myProgressTask {
// This just increases the progress indicator in a loop
float progress = 0.0f;
while (progress < 1.0f) {
progress += 0.01f;
HUD.progress = progress;
usleep(40000);
}
}
Removing the progresstask method and the showWhileExecuting code removes the progress indicator. It seems that usleep overrides everything and does not allow for the progress indicator to be hidden after the download completes and instead removes it after the 4 sec.

Answer 1

Your problem is that myProgressTask doesn't perform any actual work: your download actually happens in your dispatch_async call. Use a call like [hud showHUDAddedTo: self.navigationController.view animated:YES]; before you start your network request, so it will become hidden when your download completes. This will only show the spinning indicator, not a progress circle.
If you want the progress circle, you will need to use NSURLConnection and its associated delegate methods to track the progress of the download. Specifically, look at the connection:didReceiveResponse: method—using the expectedContentLength to calculate the percentage, using values you get from the connection:didReceiveData: method to incrementally update this progress.
Check out this question for an example of how to do this.