UINavigationBar appearance refresh?

问题:

In my iPad app I have an application settings view. One of the options lets the user switch interface color scheme. The settings view is loaded by segue to a separate view controller than my "main" app's window.

When they pick a new color I switch the colorSchemeColor variable and do this:

// set the colors and refresh the view
[[UINavigationBar appearance] setBarTintColor:colorSchemeColor];
[[UIToolbar appearance] setBarTintColor:colorSchemeColor];
[[UITabBar appearance] setBarTintColor:colorSchemeColor];

However, none of the bars change color until I exit my settings view! (When the settings window disappears, the colors for the "main" app change correctly!)

So then I tried to put this code right after to refresh the settings view:

[self.view setNeedsDisplay];
[self.view setNeedsLayout];

which didn't help. So I added this as well:

[self.navigationController.view setNeedsDisplay];
[self.navigationController.view setNeedsLayout];

This didn't work either.

How can I get my settings view to "redraw" itself when the new color is picked so the change is instantly obvious?

Thanks so much!

回答1:

The appearance proxy only affects the look of newly initialized views. Setting colors on the appearance proxy will have no effect on navigation bars that are already visible.

You'll need to manually update your current view; for example:

self.navigationController.navigationBar.barTintColor = [UINavigationBar appearance].barTintColor;

回答2:

Objective-C:

self.navigationController.navigationBarHidden = YES;
self.navigationController.navigationBarHidden = NO;

Swift:

self.navigationController?.isNavigationBarHidden = true
self.navigationController?.isNavigationBarHidden = false

回答3:

While I think Aaron Brager's answer is the ideal appraoch, my app needs about 15 different appearance settings and uses a split view controller, so I have to reapply all the setting to the global appearance and then apply them all to my two displayed views. That's a lot of redundant code.

Based on the idea that presenting and dismissing a modal view controller forces everything below it to redraw, I tried this and it worked perfectly:

UIViewController *redrawTrigger = [[UIViewController alloc] init];
redrawTrigger.modalPresentationStyle = UIModalPresentationFullScreen;
[mySplitViewController presentModalViewController:redrawTrigger animated:FALSE];
[mySplitViewController dismissModalViewControllerAnimated:FALSE];
[redrawTrigger release];