How come presentModalViewController is not working the second time? - iphone

Question

I am using a tab based application that shows a presentModalViewController called "overview" that has 2 buttons on it .
In order to call it I am using the following code in app delegate:
Overview *overview = [[Overview alloc] initWithNibName:#"Overview" bundle:nil];
[self.tabBarController presentModalViewController:overview animated:YES];
When overview shows up, it has a button called that gets clicked and I am using the following code:
-(IBAction) btnLoginPressed{
[self dismissModalViewControllerAnimated:YES]; //get rid of view
Login *login = [[Login alloc] initWithNibName:#"Login" bundle:nil];
[self.tabBarController presentModalViewController:login animated:YES];
[login release];
}
However the login prsentModalViewController never shows up. Can someone explain why and what I can do to show it?
Thanks

Answer 1

When you present a modal view controller, you do it from the view controller currently in the view.
Assuming your second modal display of a view controller is happening in Overview.m change your code to the following:
-(IBAction) btnLoginPressed {
Login *login = [[Login alloc] initWithNibName:#"Login" bundle:nil];
[self presentModalViewController:login animated:YES];
[login release];
}
You don't need to dismiss Overview first, and in fact you shouldn't as it the animations won't work in conjunction with each other.
When you ultimately dismiss login (or however deep you want to go), you send dismissModalViewController:animated: as high up as you need to. To get back to the tab bar's controller use:
[self.tabBarController dismissModalViewController:animated]
It would be well beyond the scope of your question and the time I have to answer but you should take some time and really study the docs on implementing View Controllers. I definitely recommend following Apple's code style guidelines as one suggestion to make your code much more readable (e.g. overviewViewController vs overview). It's also clear you're just learning so keep at it.