如何通过标签栏按钮显示视图控制器

Question

I have a tab bar controller with 3 tab bar buttons. At the moment it looks like this:

class CustomTabBarController: UITabBarController {

override func viewDidLoad() {
    super.viewDidLoad()

    let firstTabBarController = FirstController()
    let firstTabBarNavigationController = UINavigationController(rootViewController: firstTabBarController)
    firstTabBarNavigationController.tabBarItem.title = "First Tab"

    let secondTabBarController = SecondController()
    let secondTabBarNavigationController = UINavigationController(rootViewController: secondTabBarController)
    secondTabBarController.tabBarItem.title = "Second Tab"

    let thirdTabBarController = ThirdController()
    let thirdTabBarNavigationController = UINavigationController(rootViewController: thirdTabBarController)
    thirdTabBarNavigationController.tabBarItem.title = "Third Tab"

    viewControllers = [firstTabBarNavigationController, secondTabBarNavigationController, thirdTabBarNavigationController]

}
}

Right now, with the code above, all the view controllers are sitting inside the CustomTabBarController

I want the the middle tab bar button, the secondTabBarNavigationController to present a view controller, specifically the UIImagePickerController for a user to select an image, similar to Instagram.

How can this be achieved? I am not using storyboards

Answer 1

Just implement the func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool delegate method of the tabBar controller.

When the desired tab is pressed, present a controller and return false , otherwise return true .

I would also associate an empty UIViewController instance to the tab.

Ex.

func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
    if (tab for this controller is equal to the expected tab) {
        // present you controller
        return false
    } else {
        return true
    }
}