gistfile1.m

+ (void)displaySpinnerOverlayOver:(UIView *)view {
    UIActivityIndicatorView *spinner;
    
    if (spinnerOverlayView == nil) {
        spinnerOverlayView = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 480.0)];
        spinnerOverlayView.opaque = NO;
        spinnerOverlayView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];
        spinnerOverlayView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;;
        
        spinner = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(142.0, 222.0, 37.0, 37.0)];
        spinner.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;
        [spinnerOverlayView addSubview:spinner];
        [spinner startAnimating];
        [spinner release];
        
    } else {
        spinner = [spinnerOverlayView.subviews objectAtIndex:0];
    }
    
    spinner.center = CGPointMake(CGRectGetMidX(view.frame), CGRectGetMidY(view.frame));
    
    [view addSubview:spinnerOverlayView];
    
    spinnerOverlayView.alpha = 0.0;
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.25];
    spinnerOverlayView.alpha = 1.0;
    [UIView commitAnimations];
}

+ (void)hideSpinnerOverlay {
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(hideAnimationDidStop:finished:context:)];
    spinnerOverlayView.alpha = 0.0;
    [UIView commitAnimations];
    [spinnerOverlayView removeFromSuperview];
}

+ (void)hideAnimationDidStop:(NSString *)animationID finished:(NSNumber *)finished {
    [spinnerOverlayView removeFromSuperview];
}