当tabbar不是root视图时更改tabbar图像

Question

I am looking at changing the graphics on a tabbar, such as

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
UITabBarController *tabBarController = (UITabBarController *)self.window.rootViewController;
UITabBar *tabBar = tabBarController.tabBar;
UITabBarItem *tabBarItem1 = [tabBar.items objectAtIndex:0];
UITabBarItem *tabBarItem2 = [tabBar.items objectAtIndex:1];
UITabBarItem *tabBarItem3 = [tabBar.items objectAtIndex:2];
UITabBarItem *tabBarItem4 = [tabBar.items objectAtIndex:3];
tabBarItem1.title = @"Home";
tabBarItem2.title = @"Maps";
tabBarItem3.title = @"My Plan";
tabBarItem4.title = @"Settings";

The problem I have here is that my tabbarcontroller is not my root view, so how can I reference the tabbarcontroller to change the tab images?

I am following a suggestion from this post ( Can I have more than 1 UITabBarController? ) that refers to having a tableview that links to one or more tabbarcontrollers.

So my root view is not a tab bar, but the tab bar view is loaded after coming from one previous screen.

I have this all working, with the initial screen and then the tab bar, and everything is working fine, I just need to change the graphics on the tab bar, and am not able to do this as all tutorials on changing tab bar graphics use the app delegate and refer to the tabbarcontroller as the root view.

Any help on this greatly appreciated!

Answer 1

Tab bar items belong to the individual content view controllers in each tab, so rather than trying to reference the tab bar controller, you should change the tab item properties in those controllers. If you want those changes to be visible as soon as the tab bar controller comes on screen, you need to put those customizations in their awakeFromNib or initWithCoder methods (for controllers set up in IB).

Answer 2

Richard,

Firstly, the post you reference pointed out that this is very bad visual design, but anyway, if you need to do it.

How you reference the tab bar controller depends on how you instantiate it. This stuff should be fairly obvious, so I'm guessing that you're working with xibs or storyboards.

Either way, when you load the second view that is going to have the tab bar on it, you'll be loading a view controller to control the view. Just bind the tab bar to a property of the view controller in IB, and you can do your set up in the view did load of the view controller.

Actually, if you're using IB ( XIB or storyboards), you can just set up your icons there.