Question

I have a UITabBarConroller that I use to switch between 3 different views. This all works perfectly. On one of my tabs, I added a button at the to called “Add”, I have added an outlet to this, as well as an IBAction method which looks like the following:

// Method used to load up view where we can add a new ride
- (IBAction)showAddNewRideView {    

    MyRidesViewController *controller = [[MyRidesViewController alloc] initWithNibName:@"AddNewRide" bundle:nil];
    controller.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentModalViewController:controller animated:YES];
    [controller release];

}//end showAddNewRideView

This currently works fine, and loads up my AddNewRide nib file. But, once that view loads, I have a cancel button, which, when clicked, I want to return to the previous view. So, I figured I would just do the reverse of the above, using the following method which would load back my previous nib:

- (IBAction)cancelAddingNewRide {
    MyRidesViewController *controller = [[MyRidesViewController alloc] initWithNibName:@"MainWindow" bundle:nil];
    controller.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentModalViewController:controller animated:YES];
    [controller release];

}//end cancelAddingNewRide

But, which trying to load the MainWindow nib, the program crashes, and I get the following error:

2010-05-05 20:24:37.211 Ride[6032:207] *** -[MyRidesViewController cancelAddingNewRide]: unrecognized selector sent to instance 0x501e450
2010-05-05 20:24:37.213 Ride[6032:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[MyRidesViewController cancelAddingNewRide]: unrecognized selector sent to instance 0x501e450'

So, I am a little lost as to why it would work one way, but not the other.

Answer 1

First, I wanted to address part of the error: Think of your views as a stack. When you “push” a modal controller, you are adding that view to a stack. The old view is still there underneath. So you need to “pop” off the modal view to return to the old view. If you push a new view on, you now have 3 views on the stack which are all taking up memory, where you really only need one.

So, inside cancelAddingNewRide just try:

[super dismissModalViewControllerAnimated:true];

You may have other issues that are causing the crash, but this should generally get things working.