Open iPhone SDK: Building a UIProgressBar

@implementation SampleApp
#define STYLE 0

- (void) handleTimer: (id) timer
{
    amt += 1;
    [progbar setProgress: (amt / 20.0)];
    if (amt > 20.0) {[alert dismiss]; [timer invalidate];}
}

- (void) applicationDidFinishLaunching: (id) unused
{
    UIImage *img = [UIImage applicationImageNamed:@"Default.png"];
    UIImageView *imgView = [[UIImageView alloc] initWithImage:img];

    struct CGRect rect = [UIHardware fullScreenApplicationContentRect];
    UIWindow *window = [[UIWindow alloc] initWithContentRect: rect];
    [window orderFront: self];
    [window makeKey: self];
    [window setContentView: imgView];

    // Create an otherwise-empty alert sheet
    alert = [[UIAlertSheet alloc] 
		initWithTitle:@"Updating Database"
		buttons:NULL
		defaultButtonIndex:0
		delegate:self
		context:self];
    [alert setBodyText:@"Please wait...\n\n\n\n"];

    // Create the progress bar and add it to the alert
    progbar = [[UIProgressBar alloc] initWithFrame:
                 CGRectMake(50.0f, 70.0f, 220.0f, 90.0f)];
    [alert addSubview:progbar];
    [progbar setStyle: STYLE];
    [alert presentSheetInView:imgView];

    // This timer takes the place of a real task
    amt = 0.0;
    id timer = [NSTimer scheduledTimerWithTimeInterval: 0.5
                 target: self
                 selector: @selector(handleTimer:)
                 userInfo: nil
                 repeats: YES];
}
@end