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Posts Tagged ‘delay’

I’ve recently been working on an app for the iPad and ran into some strange issue, when using a modalViewController. In my case, I wanted the modalViewController to show up right after the app finished launching. I also had a pretty basic viewController setup, similar to the one you get when using the “View-based Application” template.

Inside my rootViewController I wanted to call some other viewController as modalViewController right after start up. It looked pretty much like this:

- (void)viewDidLoad {
    [super viewDidLoad];

    //instantiate otherViewController and call it as modalViewController
    OtherViewController *viewController = [[OtherViewController alloc] initWithNibName:@"OtherWindow" bundle:nil];
    self.otherViewController = viewController;
    [viewController release];

    [self presentModalViewController:otherViewController animated:YES];
}

Unfortunately, when I tested my app nothing happened. The reason why no errors or warnings were shown was simple: The code was fine.
So, what was the problem then? After doing some investigation I found out, that the modalViewController didn’t like being called directly from viewDidLoad. Instead I had to call it with just a tiny bit of a delay.

So, I added a new method to my class:

- (void)callOtherViewController {
    if (otherViewController == nil) { //only allocate, if it has not been allocated yet
        //instantiate otherViewController and call it as modalViewController
        OtherViewController *viewController = [[OtherViewController alloc] initWithNibName:@"OtherWindow" bundle:nil];
        self.otherViewController = viewController;
        [viewController release];
    }

    [self presentModalViewController:otherViewController animated:YES];
}

Finally, I only had to call this method from viewDidLoad with the delay mentioned above, like this:

- (void)viewDidLoad {
    [self performSelector:@selector(callOtherViewController) withObject:nil afterDelay:0.1f];
}

That did the trick!