在 NavigationController 后退按钮处委托 / 展开 Segue

Question

i have an app with three views:

• FirstView
• SecondView
• ThirdView

When i am on the ThirdView and i click on the back button from navigation controller, i want to pass data from ThridView to SecondView. But i don't know how to do this.

I don't want to add an extra button on my view.

The same when i'm on the SecondView and i want to go back to the FirstView. I can't use the method "ViewWillDisappear" because if a set a "PerformSegueWithIdentifier" on this method to pass data from SecondView to FirstView, i can't switch to ThirdView because the "ViewWillDisappear" method will be executed.

Can you please help me?

PS: I use the language swift 2

Answer 1

In your viewWillDisappear or viewDidDisappear method you can check if back button is pressed by checking whether or not your view controller is moving from parent view controller.

override func viewWillDisappear(animated: Bool) {

    if(self.isMovingFromParentViewController())
    {
        //Send data to previous view controller
        print("Going back: Back button pressed");
    }else{
        print("Controller is hidden due to some other reason e.g Pushing another view controller");
    }
}

Answer 2

I make subclass of UINavigationController because I cannot find Unwind Segue signature in UIViewController since Xcode 11.

@implementation CLUnwindNavigationController

- (BOOL)canPerformUnwindSegueAction:(SEL)action fromViewController:(UIViewController *)fromViewController withSender:(id)sender {
    return NO;
}

- (IBAction)unwindForSegue:(UIStoryboardSegue *)unwindSegue towardsViewController:(UIViewController *)subsequentVC {
}

@end

You can find UnwindSegue signature.

You can connect to your desired action.