Question

I have a UIViewController (MyViewController) and another view controller i’m presenting modally though MyViewController (call it SecondViewController). I want to be able to send a message to MyViewController from SecondViewController by using

[self.parentViewController hideSecondViewController];

But since parentViewController is defined as a UIViewController, and hideSecondViewController isn’t a method of UIViewController, I get a warning saying “UIViewController may not respond to ‘hideSecondViewController'”. It works fine, because it CAN send the message successfully during the program, but since I #import SecondViewController in MyViewController, I can’t #import MyViewController in SecondViewController. Any way around this?

Answer 1

When it comes time to dismiss a modal
view controller, the preferred
approach is to let the parent view
controller do the dismissing. In other
words, the same view controller that
presented the modal view controller
should also take responsibility for
dismissing it whenever possible.
Although there are several techniques
for notifying a parent view controller
that it should dismiss its modally
presented child, the preferred
technique is delegation.

In a delegate-based model, the view
controller being presented modally
must define a protocol for its
delegate to implement. The protocol
defines methods that are called by the
modal view controller in response to
specific actions, such as taps in a
Done button. The delegate is then
responsible for implementing these
methods and providing an appropriate
response. In the case of a parent view
controller acting as a delegate for
its modal child, the response would
include dismissing the child view
controller when appropriate.

Read more at the View Controller Programming Guide for iOS.

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P.S:

since I #import SecondViewController
in MyViewController, I can’t #import
MyViewController in
SecondViewController.

To solve a circular dependency problem you can use a forward declaration.