Abort navigation back if unsaved changes (ios7)

Question

I want to prompt the user to save changes before they navigate back out of editing an entity in my IOS7 application.

An early stack overflow said I can detect this will happen at this point here: but I've been unable to abort the navigation.

-(void)willMoveToParentViewController:(UIViewController *)parent {
NSLog(@"\t\t\tThis VC has has been pushed popped OR covered");

if (!parent) {
    NSLog(@"\t\t\tThis happens ONLY when it's popped");

}

}

basically if my managedObjectContext has unsaved changes I'd like to pop an alert box before the back navigation event happens. Any ideas?

I tried this solution: https://stackoverflow.com/a/19210888/2069812 but doesn't seem to work.

Normally, you need to intercept and check before allowing user to navigate away from any view. — user523234, Jul 15 '14 at 16:24

ninjapro · Answer 1 · 2014-07-15T16:23:43.163

1

You can use custom back button and handle its touch event yourself. It's the simplest solution in this case.

For example:

self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Button" style: UIBarButtonItemStylePlain target:self action:@selector(buttonDidTouch:)];

- (void)buttonDidTouch:(id)sender)
{
    if (edited) {
        [self.navigationController popViewControllerAnimated:YES];
    } else {
        // Do your stuffs
    }
}

edited Jul 15 '14 at 16:23

answered Jul 15 '14 at 16:16

ninjapro

107
5

Please add further details when answering a question to make it easier for the OP and future users to understand. – Deepend Jul 15 '14 at 16:23
Sorry for that, added example – ninjapro Jul 15 '14 at 16:30
No problem. Its full authoritative answers which make this site useful. its easier for people to quickly decide if the answer is useful to them or not. – Deepend Jul 15 '14 at 16:39

score 0 · Answer 2 · edited May 23 '17 at 12:09

0

I know my answer is not using -(void)willMoveToParentViewController:(UIViewController *)parent, but the easiest would be to just display no back button.

This can be done via:

self.navigationItem.hidesBackButton = YES;

You can also disable the swipe gesture as described here:

if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
    self.navigationController.interactivePopGestureRecognizer.enabled = NO;
}

But if you really want to hack in there then I would try a custom back button and handle the action in the controller.

edited May 23 '17 at 12:09

Community

1
1

answered Jul 15 '14 at 16:07

lukaswelte

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But I still need a back button... how do you suggest i go about that? – Jeef Jul 15 '14 at 16:11
edited my answer with a try, but I'm not sure if this can work.. cause usually these delegate methods are just invoked to react to it in order to save this data for example. – lukaswelte Jul 15 '14 at 16:13
I'll give that a shot... it looks like you are trying to hack the navStack and push yourself back on? – Jeef Jul 15 '14 at 16:13
Yes, that would be my try. There is no nice API for interfering this pop back of the navigation controller – lukaswelte Jul 15 '14 at 16:14
The other possibility would be setting a custom back button in the navbar. This would enable you to receive the action of the button and react like you want it to. – lukaswelte Jul 15 '14 at 16:17
@lukaswelte, the only issue with hiding the back button is that the user still can swipe back to recent view controller in iOS7+. – holex Jul 15 '14 at 16:27

score 0 · Answer 3 · answered Jul 15 '14 at 16:29

0

I just made a custom button in IB and attached to it. Issue solved.

answered Jul 15 '14 at 16:29

Jeef

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Abort navigation back if unsaved changes (ios7)

3 Answers3