Swift 4 - How to override tab bar will open view controller

Question

Is it possible that when a user clicks on a Tab bar item that I can override this in the UITabBarController , where I then check a UserDefault which then decides whether I show the view or return and they stay on their current view ?

It would be something like this:

override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
    if item.image == UIImage(named: "TabProfile")
    {
        // Profile tab selected
        if !loginController.isUserLogged()
        {
            // Not logged in...
            showLoginView()  

            // Following line doesn't work...
            tabBarController?.selectedIndex = selectedIndex
        }
    }
}

If possible I want to perform this check and if false then actually prevent the view from even reaching viewDidLoad.

Thanks.

Wouldn't it be better to avoid adding the tab at all until the user is logged in? Or at least disable the tab bar item until the user logs in? — rmaddy, Jan 10 '19 at 23:13
@rmaddy I thought about this, but I want the user to be able to navigate all content without having to create an account. — Niall Kiddle, Jan 10 '19 at 23:36
Your whole question is asking how to conditionally prevent a user from selecting a tab. Maybe I put the wrong condition in my comment but it still stands. Don't add (or just disable) the tab until the condition is met. — rmaddy, Jan 10 '19 at 23:38
In this case the interaction between the guest user and the profile tab bar item displays the login popup. Which is the desired functionality. Maybe I worded the question wrong and didn't given enough context. Thank you, anyway — Niall Kiddle, Jan 10 '19 at 23:42

score 2 · Accepted Answer · answered Jan 10 '19 at 23:16

I guess you need

func tabBarController(_ tabBarController: UITabBarController, 
              shouldSelect viewController: UIViewController) -> Bool {
   if let ind = tabBarController.viewControllers!.index(of:viewController) , ind == 2 { // suppose profile is 2
      // 
       if userNotLogged { 
         // present modal login view 
         return false
       } 
   } 
  return true
}

Swift 4 - How to override tab bar will open view controller

1 Answers1