标签栏上的iOS更改

Question

I want to know when the tab in the tab bar changes, so that i can report it to Firebase Analytics. How do i do this.

I tried this

override func viewDidAppear(_ animated: Bool) {
    Analytics.logEvent("projects_open", parameters: [:])
}

But i have a feeling that what would also run when i go back to it from another ViewController. I need something that can detect when a tab is opened, not when it becomes visible.

Is there another func that works for this?

Answer 1

Swift 3.0

Use this two delegate methods, and don't forget to assign delegate to self.

func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
    //MARK: - UITabBarControllerDelegate
}

override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
   //MARk: - UITabBarDelegate
}

Answer 2

There is a delegate function on UITabbarController for detecting that a tab was selected:

func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController)

You can also access the selected index like this:

tabController.selectedIndex

Answer 3

If you use only tabBar.in viewDidLoad set tabBar delegate to self and

override func tabBar(_ tabBar: UITabBar, didSelect item:UITabBarItem) 
{
       //MARk: - UITabBarDelegate
if(tabBar.selectedIndex == 0) {
 //Do something
}
else if(tabBar.selectedIndex == 1) {
 //Do something.
} 
}

and if you use tabBarController use this method.And mark delegate as self

func tabBarController(_ tabBarController: UITabBarController, 
didSelect viewController: UIViewController) {
}

Very important Note:

If you want to save which tabBar was previously selected you have to save it on your way.Either use flag or NSUserDefaults according to your wish. The reason i mentioned this because i needed to check which tab has been selected right now in View in one of my project.

Answer 4

Swift 5

Easy way just click on link StakOverFlow screen will open https://stackoverflow.com/a/60539396/6881070