I found, what I think to be, a decent example project on singleton classes here.
My question is:
What's up with
- (void)textFieldDidEndEditing:(UITextField *)textField
inside of the RootViewController.m and the SecondViewController.m (around lines 45-ish)? I understand how it works, but I don't see how it ever gets called or used.
They are triggered by delegation. If you check the nib (in IB), you will see that it has delegate the first responder or the class (RootViewController or SecondViewController).
So what it does is listen to the textfield for once the user presses the OK button to trigger the method above (which is defined to UITextFieldDelegate protocol).