Programmatically switching between tabs within Swift

Question

I need write some code to switch the view to another tab when the iOS app starts  so  for example  the second tab is shown by default rather than the first    I m new to Swift  and have worked out the following    The code should probably go in the override func viewDidLoad   function of the ViewController of the first tab  The following code shows the second ViewController  but not with the tab bar at the bottom  vcOptions is the second ViewController tab item    let vc   AnyObject    self storyboard instantiateViewControllerWithIdentifier  vcOptions   self showViewController vc as UIViewController  sender  vc    I think the answer may lie in using the UITabbarController selectedIndex   1  but not quite sure how to implement this

User · Answer

In a typical application there is a UITabBarController and it embeds 3 or more UIViewController as its tabs. In such a case if you subclassed a UITabBarController as YourTabBarController then you can set the selected index simply by:

selectedIndex = 1 // Displays 2nd tab. The index starts from 0.

In case you are navigating to YourTabBarController from any other view, then in that view controller's prepare(for segue:) method you can do:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destination.
        // Pass the selected object to the new view controller.
        if segue.identifier == "SegueToYourTabBarController" {
            if let destVC = segue.destination as? YourTabBarController {
                destVC.selectedIndex = 0
            }
        }

I am using this way of setting tab with Xcode 10 and Swift 4.2.

User · Answer

1 Create a new class which supers UITabBarController  E g   class xxx  UITabBarController   override func viewDidLoad             super viewDidLoad       2 Add the following code to the function viewDidLoad     self selectedIndex   1    set the tab index you want to show here  start from 0   3 Go to storyboard  and set the Custom Class of your Tab Bar Controller to this new class   MyVotes1 as the example in the pic

User · Answer

Swift 5    MARK - if you are in UITabBarController  self selectedIndex   1   or   tabBarController  selectedIndex   1

User · Answer

To expand on  codester s answer  you don t need to check and then assign  you can do it in one step   func application application  UIApplication   didFinishLaunchingWithOptions launchOptions  NSDictionary   - gt  Bool          Override point for customization after application launch       if let tabBarController   self window  rootViewController as  UITabBarController           tabBarController selectedIndex   1            return true

User · Answer

If you want to do this from code that you are writing as part of a particular view controller  like in response to a button press or something  you can do this   IBAction func pushSearchButton   sender  UIButton         if let tabBarController   self navigationController  tabBarController            tabBarController selectedIndex   1          And you can also add code to handle tab switching using the UITabBarControllerDelegate methods  Using tags on the base view controllers of each tab  you can see where you are and act accordingly   For example func tabBarController   tabBarController  UITabBarController  shouldSelect viewController  UIViewController  - gt  Bool               if we didn t change tabs  don t do anything     if tabBarController selectedViewController  tabBarItem tag     viewController tabBarItem tag           return false                if viewController tabBarItem tag    4096      some particular tab            do stuff appropriate for a transition to this particular tab           else if viewController tabBarItem tag    2048      some other tab            do stuff appropriate for a transition to this other tab

User · Answer

If your window rootViewController is UITabbarController which is in most cases  then you can access tabbar in didFinishLaunchingWithOptions in the AppDelegate file   func application application  UIApplication   didFinishLaunchingWithOptions launchOptions  NSDictionary   - gt  Bool          Override point for customization after application launch       if let tabBarController   self window  rootViewController as  UITabBarController           tabBarController selectedIndex   1            return true     This will open the tab with the index given  1  in selectedIndex   If you do this in viewDidLoad of your firstViewController  you need to manage by flag or another way to keep track of the selected tab   The best place to do this in  didFinishLaunchingWithOptions of your AppDelegate file or rootViewController custom class viewDidLoad

User · Answer

Just to update  following iOS 13  we now have SceneDelegates  So one might choose to put the desired tab selection in SceneDelegate swift as follows   class SceneDelegate  UIResponder  UIWindowSceneDelegate        var window  UIWindow       func scene   scene  UIScene                  willConnectTo session  UISceneSession                  options connectionOptions  UIScene ConnectionOptions             guard let      scene as  UIWindowScene  else   return            if let tabBarController   self window  rootViewController as  UITabBarController               tabBarController selectedIndex   1

User · Answer

Swift 3  You can add this code to the default view controller  index 0  in your tabBarController       override func viewWillAppear   animated  Bool                self tabBarController  selectedIndex   1         Upon load  this would automatically move the tab to the second item in the list  but also allow the user to manually go back to that view at any time

User · Answer

The viewController has to be a child of UITabBarControllerDelegate  So you just need to add the following code on SWIFT 3              self tabBarController  selectedIndex   1

[ios] Programmatically switching between tabs within Swift

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