Quickly add a simple UIActivityIndicator to your screen

Sometimes you need to quickly throw a progress indicator over your view while something processes (hopefully in the background).

I've found this code to be useful for that situation. Apply to your needs.

UIActivityIndicatorView *activityIndicatorView = [[UIActivityIndicatorView alloc] initWithFrame:self.view.frame];
activityIndicatorView.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;
activityIndicatorView.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.5];
[self.view addSubview:activityIndicatorView];
[activityIndicatorView startAnimating];

[self.presentingViewController dismissViewControllerAnimated:YES completion:^{
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0ul);
    dispatch_async(queue, ^{
        // do your processing in the background here
        dispatch_sync(dispatch_get_main_queue(), ^{
            // Update UI
            [activityIndicatorView stopAnimating];
            [activityIndicatorView removeFromSuperview];
        });
    });
}];