如何使用 StoryBoard 在 UITabBarController 中设置选定的选项卡？

Question

How can I switch to some tab in UITabBarController using StoryBoard? I have tried the code below but without success (the tab is not selected):

self.tabBar.selectedIndex = 3;

Honestly I used nib files without StoryBoard and this code above worked fine in

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions
          :(NSDictionary *)launchOptions

but now I can't set the tab programatically. Maybe there is another problem that is not connected to selecting the tab. How can I switch tabs?

Answer 1

获取您的UITabBarController实例，然后设置selectedViewController属性：

yourTabBarController.selectedViewController=[yourTabBarController.viewControllers objectAtIndex:3];//or whichever index you want

Answer 2

Alexander, I think your problem is getting correct instance of your tab bar. If your tab bar is your root view controller, then you can do it like this in your appdelegate if didFinishLoading method:

UITabBarController *tabBar = (UITabBarController *)self.window.rootViewController;
    [tabBar setSelectedIndex:3];

Give it a try and tell me the result please.

Answer 3

*Swift Comment - 18 months later if you convert Yanchi's solution into Swift in your appDelegate you'll get the expected result. The Swift translation is:

let tabBar: UITabBarController = self.window?.rootViewController as! UITabBarController

tabBar.selectedIndex = 1

Answer 4

This will work in stroryboard too...

[self.tabBarController setSelectedIndex:3]; with this add UITabBarControllerDelegate in .h

and then use this delegate method

- (BOOL)tabBarController:(UITabBarController *)theTabBarController shouldSelectViewController:(UIViewController *)viewController
{
    return (theTabBarController.selectedViewController != viewController);
}

Answer 5

You can achieve this also using storyboards only. Ctrl-drag from the tabBarController to your ViewController(s), and select 'Relationship Segue, View controllers'. The first ViewController you select will be the default/initial ViewController.

Answer 6

I'm using IBInspected in LSwift :

extension UITabBarController {
    @IBInspectable var selected_index: Int {
        get {
            return selectedIndex
        }
        set(index) {
            selectedIndex = index
        }
    }
}

Answer 7

Swift 4.1

In your TabBarViewController class, you can add this key line

self.selectedIndex = 0

Answer 8

Here is what I do (Swift 5.x):

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        if let tabBarController = self.window?.rootViewController as? UITabBarController {
            if let viewControllers: [UIViewController] = tabBarController.viewControllers {
                tabBarController.selectedIndex = viewControllers.count-1
            }
        }
        return true
    }

Answer 9

Swift 5.3

Let tabBar be an instance of UITabBarController then :

tabBar.selectedViewController = tabBar.viewControllers![2]

Note:
Instead of 2, put your desired viewController's index

Answer 10

You can also set the default tab in "User Defined Runtime Attributes" using storyboard.

Select your Tab Bar Controller from storyboard, in the right pane select Identity Inspector and add an attribute:

Key Path : selectedIndex
Type     : Number
Value    : 2 ( whatever number you want )