viewWillAppear in viewcontrollers of a tabbar

Question

In my tab-bar I have four viewcontrollers, and what happens in one can affect the view of the other, so I may need to reload some elements in the viewcontroller when it becomes visible. Normally I'd fix that by implementing viewWillAppear, but when I switch between the tabs, viewWillAppear does not seem to get called. How can I fix that, or what should I do instead?

Update: as a PS I should add that this is a tabbarcontroller in a navigationcontroller hierarchy

Cheers

Nik

Maryalice

I'm not sure it is same problem... but might worth to loot #131562 – Dissever

Answer 1

viewWillAppear should only be used when the view appears, and not for updating it.

Use setNeedsDisplay on the viewController's view instead.

Interlunar

Where would I call setNeedsDisplay from? The problem is that I need a hook for when the user chooses a new viewcontroller from the tabbar – Maryalice

Oh, sory, I mixed up things here a little bit. I'm not sure why the viewWillAppear is not getting called, but I know a way around it: Make some object a tabBarController delegate, and it will the send the message, that a new view was selected, and call view will appear from there. – Interlunar

Sounds like an interesting idea, I'll give that a try tomorrow :-) – Maryalice

Answer 2

You may use the tabbar controller delegate works like a charm

-(void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    [viewController viewWillAppear:YES];

}

Agonistic

Answer 3

Please see my answer here

iPhone viewWillAppear not firing

Tresa

Answer 4

And in case you find this question because you would like to update something in the UITabBarController itself, not the UIViewControllers of a UITabBarController, like the OP's question. For example, hiding or displaying a custom UITabBarButton. In Swift 3.0 overriding setNeedsStatusBarAppearanceUpdate of my UITabBarController class worked for me.

override func setNeedsStatusBarAppearanceUpdate() {

}

Graphology