Action to Navigation bar back button

Question

I want to show an alert with Confirmation when user clicks on back button. This is how I'm trying to add action.

self.navigationItem.hidesBackButton = true
let newBackButton = UIBarButtonItem(title: "<", style: UIBarButtonItemStyle.plain, target: self, action: #selector(ViewController.save(sender:)))
self.navigationItem.leftBarButtonItem = newBackButton

This is working fine but I want the default back button image in it and not the custom title. How to do that ?

I tried following code as well :

self.navigationItem.backBarButtonItem?.action = #selector(ViewController.save(sender:))

...but the action is not performed, too.

I think you just can set the properly image of back arrow, here is the [assets](http://stackoverflow.com/a/30110190/4929876) download it and add it to the custom back button. — Santiago Carmona González, Feb 08 '17 at 04:25
self.navigationItem.hidesBackButton = true; If it's true? That means you cannot get the standard back button and their icon too. — Mannopson, Feb 08 '17 at 05:44
@Nitesh I have the same problem, perhaps it's a bug. I have used the Swift 3.0 and Xcode 8.0 — Mannopson, Feb 08 '17 at 05:47
@Nitesh have you already tried my suggested solution by using `UINavigationControllerDelegate` methods? — regetskcob, Feb 08 '17 at 09:12

Amit Tandel · Answer 1 · 2017-02-08T11:46:42.103

5

This might help. This wont override back action, but you can do additional task.

Objective c

-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    if(self.isMovingFromParentViewController)
    {
        //On click of back or swipe back
    }
    if(self.isBeingDismissed)
    {
        //Dismissed
    }
    NSLog(@"%d",self.isBeingDismissed);
    NSLog(@"%d",self.isMovingFromParentViewController);
}

Swift

override func viewWillDisappear(_ animated: Bool)
{
    super.viewWillDisappear(animated);
    if self.isMovingFromParentViewController
    {
        //On click of back or swipe back
    }
    if self.isBeingDismissed
    {
        //Dismissed
    }
}

edited Feb 08 '17 at 11:46

answered Feb 08 '17 at 09:24

Amit Tandel

883
7
16

but alert is not presented if I do it by this way. – Nitesh Feb 08 '17 at 09:26
Alert wont be shown on this view controller because it is about to be disappear. try showing on previous view controller which will be shown. – Amit Tandel Feb 08 '17 at 09:34

score 2 · Answer 2 · answered Jun 03 '20 at 21:29

I found a solution!

I tested it on iOS 11 and iOS 13 and it works fine :)

protocol CustomNavigationViewControllerDelegate {
    func shouldPop() -> Bool
}

class CustomNavigationViewController: UINavigationController, UINavigationBarDelegate {
    var backDelegate: CustomNavigationViewControllerDelegate?

    func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
        return backDelegate?.shouldPop() ?? true
    }
}

class SecondViewController: UIViewController, CustomNavigationViewControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()

        (self.navigationController as? CustomNavigationViewController)?.backDelegate = self
    }

    func shouldPop() -> Bool {
        if (needToShowAlert) {
            showExitAlert()
            return false

        } else {
            return true
        }
    }
}

Thanks, this works well for me. However, don't you need to clear backDelegate when SecondViewController disappears? — Preston Landers, Nov 11 '20 at 17:41

score 1 · Answer 3 · answered Feb 08 '17 at 06:50

You need add custom back button to Navigation bar, and add action to it

      let backButton = UIBarButtonItem (image: UIImage(named: "ico-nav-prev")!, style: .plain, target: self, action: #selector(GoToBack))
      self.navigationItem.leftBarButtonItem = backButton
      self.navigationItem.hidesBackButton = true

     func GoToBack(){

        self.navigationController!.popViewController(animated: true)

      }

regetskcob · Answer 4 · 2017-02-08T06:43:43.323

0

I don't know what you try to achive, but isn't it a possible solution to do, what you want, whenever vieWillDisappear: got called? This is maybe a matching entrypoint without fiddeling around with the back-bar-button suggested in the other answers.

Better Another option would be to implement the UINavigationControllerDelegate, set your controller as delegate and then implement your alert in navigationController(_:willShow:animated:).

Take a look here for reference.

edited Feb 08 '17 at 06:43

answered Feb 08 '17 at 06:38

regetskcob

1,172
1
13
35

I need to display an alert when user press the back button. Alert will have button with "Yes" and "No". I tried it on viewWillDisappear but my alert was not presented on it – Nitesh Feb 08 '17 at 06:41
Added another option that should fit in your situation. – regetskcob Feb 08 '17 at 06:44
It is gets called when view is presented and every time on push, etc. I want it only on back. – Nitesh Feb 08 '17 at 09:19
@Nitesh you have to check whether the `viewController`that will be shown is the one you want to show the alert before and then you're done! – regetskcob Feb 08 '17 at 09:36

score 0 · Answer 5 · edited May 23 '17 at 12:01

I think this answer should do the job.

You basically create your button with the default style and register a selector.

And you might try this for a backButton instead of leftButton:

Objective-C

UIBarButtonItem *backBtn = [[UIBarButtonItem alloc] init];
[desVC.navigationItem setBackBarButtonItem:backBtn];

Swift

let backBtn = UIBarButtonItem()
self.navigationItem.backBarButtonItem = backBtn

Mannopson · Answer 6 · 2017-02-08T18:14:24.980

Call this line of code inside of your ParentViewController's viewDidLoad method not the ChildViewController

self.navigationItem.backBarButtonItem = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)

Remove the following line of code from your ChildViewController

self.navigationItem.hidesBackButton = true

And you'll be Ok! If you need to create an action for this transition, I mean whenever the user taps the back button from your ChildViewController. Simply call this method inside of your ChildViewController

 override func didMove(toParentViewController parent: UIViewController?) {
    super.didMove(toParentViewController: parent)

    if parent == nil {

    } else {

    }
}

Edited:

ChildViewController

 override func didMove(toParentViewController parent: UIViewController?) {
    super.didMove(toParentViewController: parent)

    if parent == nil {
        NotificationCenter.default.post(name: NSNotification.Name.init("Post"), object: nil)
    } else {

    }

}

ParentViewController

 override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    NotificationCenter.default.addObserver(self, selector: #selector(self.handler(notification:)), name: NSNotification.Name.init(rawValue: "Post"), object: nil)

}

func handler(notification: Notification) {

    let alertController = UIAlertController(title: "Hello", message: nil, preferredStyle: .alert)
    alertController.addAction(UIAlertAction(title: "Dismiss", style: .default, handler: nil))
    self.present(alertController, animated: true, completion: nil)

}

This is works but with a problem like so:

Warning: Attempt to present on while a presentation is in progress!

Therefore I don't recommended. Good luck

My main purpose of doing this is to display an alert when back is pressed. — Nitesh, Feb 08 '17 at 17:54
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/135199/discussion-between-mannopson-and-nitesh). — Mannopson, Feb 08 '17 at 18:14

Action to Navigation bar back button

6 Answers6

Linked