Question

I have a cancel button, when i press cancel button then i pop my current viewcontroller. Before popping my controller, i want to access one member (which is a class Student) of previous view controller. So i am doing this way:

StudentProfileViewController *controller = (StudentProfileViewController*)self.parentViewController;
    NSLog(@"%@", controller.student);

My app crashes on line NSLog, error is this:

[UINavigationController student]: unrecognized selector sent to instance 0x6865180

Strange part is its says “[UINavigationController student]” but my controller is UIViewController.

Can anyone shed a light on this. I know some silly mistake is being done.

Thanks

Answer 1

The parentViewController would return the controller you are looking for only if you had presented modally from that view in the first place. It looks to be that you are trying to reference the previous controller in the stack, not the presenting view.
In your case, the parentViewController is the navigationController if that is how you presented. You are casting it to the controller class you wish it to be but that doesn’t make it so.
More appropriate method would be to have passed the object you wish to reference in the init method or, most preferably, make a delegate method to tell the former view when this controller is complete, then let the former view react as intended.