Something like prepareForSegue but for when going back

Question

In my iOS app, I'm using a UINavigationController with segues setup in Xcode. For one of the views, I want to hide the navigation bar, and for the others, I want it to show up. I am able to successfully hide the bar in the main view, then nicely animate it in when I segue to the next view, but when I go back (using the back button in the navigation bar), the bar just disappears, leaving a black rectangle, then switches back to the previous view. I would like to be able to catch this, with something like the opposite of prepareForSegue, and nicely animate the navigation bar out. Is there some way to do this?

score 2 · Accepted Answer · edited Mar 01 '17 at 12:37

There currently is no prepareForDesegue:sender: alternative to prepareForSegue:sender:. The recommended practice is to establish a reference, in the destination ViewController, back to the source ViewController. Then, when the destination ViewController is dismissed, it can notify the source ViewController that it is about to become the top ViewController again. Typically, the reference is established in prepareForSegue:sender:.

So, to make this concrete, let's suppose that you have ViewControllerA, and are about to segue to ViewControllerB. In ViewControllerB, you would define a property that references ViewControllerA. (This is often done using protocols, but to make it simple, just assume that ViewControllerB has @property ViewControllerA *delegate;.) Then, in prepareForSegue:sender:, you would do the following:

ViewControllerB * vcB = (ViewControllerB *)[segue destinationViewController];
vcB.delegate = self;

Later, in ViewControllerB, in whatever code is about to get you back to ViewControllerA, you would use self.delegate to reach back to ViewControllerA, and let it know it's about to be presented, and give it the opportunity to do whatever you need to with the UINavigationBar.

score 0 · Answer 2 · answered Feb 12 '12 at 18:34

In the view's UIViewController that you want the navigation bar to appear, place the following methods:

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    [self.navigationController setNavigationBarHidden:YES animated:animated];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];


    [self.navigationController setNavigationBarHidden:NO animated:animated];
}

You can add some logic in case you want the bar to stick around for any reason (like certain next views still need the bar).

Yes, thats the thing, if I segue forward, I want the bar to stick around, but only if I go back, I want to animate it away. What kind of logic can I use to do that? — Brice, Feb 12 '12 at 22:37

Something like prepareForSegue but for when going back

2 Answers2