Hi,

I've got a while loop, that runs for many seconds and that's why I want to update a progress bar (NSProgressIndicator) during that process, but it updates only once after the loop has finished. The same happens if I want to update a label text, by the way.

I believe, my loop prevents other things of that application to happen. There must be another technique. Does this have to do with threads or something? Am I on the right track? Can someone please give me a simple example, how to “optimize” my application?

My application is a Cocoa Application (Xcode 3.2.1) with these two methods in my Example_AppDelegate.m:

// This method runs when a start button is clicked.
- (IBAction)startIt:(id)sender {
    [progressbar setDoubleValue:0.0];
    [progressbar startAnimation:sender];
    running = YES; // this is a instance variable

    int i = 0;
    while (running) {
        if (i++ >= processAmount) { // processAmount is something like 1000000
            running = NO;
            continue;
        }

        // Update progress bar
        double progr = (double)i / (double)processAmount;
        NSLog(@"progr: %f", progr); // Logs values between 0.0 and 1.0
        [progressbar setDoubleValue:progr];
        [progressbar needsDisplay]; // Do I need this?

        // Do some more hard work here...
    }
}

// This method runs when a stop button is clicked, but as long
// as -startIt is busy, a click on the stop button does nothing.
- (IBAction)stopIt:(id)sender {
    NSLog(@"Stop it!");
    running = NO;
    [progressbar stopAnimation:sender];
}

I'm really new to Objective-C, Cocoa and applications with a UI. Thank you very much for any helpful answer.