shouldSelect method of UITabBarControllerDelegate never invoked

Question

I am using Swift 4 and XCode 9. I am trying to programmatically control navigation in my UITabBarController. According to Apple's documentation, I need to implement the UITabBarControllerDelegate protocol. However, the method I implemented never get called:

import UIKit

class TabBarController: UITabBarController, UITabBarControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()

        tabBarController?.delegate = self
    }

    func tabBarController(_ tabBarController: UITabBarController,
            shouldSelect viewController: UIViewController) -> Bool {
        print("Should go here...")
        return true
    }
}

Any idea what I am doing wrong?

I suspect there's some typographic error that makes your method not match up with the delegate method it's meant to override, but I can't find the difference — Alexander, Jan 19 '18 at 00:44
@Alexander All the methods in the delegate are optional, so no `override` keyword required. The issue was answered correctly, I was not properly initializing the controller. — Phil, Jan 19 '18 at 02:11

score 6 · Accepted Answer · answered Jan 19 '18 at 00:43

6

Your problem is that you are setting the wrong delegate. Update viewDidLoad to:

override func viewDidLoad() {
    super.viewDidLoad()

    self.delegate = self // or just "delegate = self"
}

The idea is that you want this tab controller to be its own delegate.

answered Jan 19 '18 at 00:43

rmaddy

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Why bother with that at all. As far as I know he can just remove UITabBarControllerDelegate from the declaration – Leo Dabus Jan 19 '18 at 00:44
2

@LeoDabus Not if he wants the tab controller to dictate whether a given tab can be selected or not. – rmaddy Jan 19 '18 at 00:45
1

`UITabBarController` doesn't implement `UITabBarControllerDelegate`. – mugx Jan 19 '18 at 00:47
@AndreaMugnaini just saw that it conforms to `UITabBarDelegate` not `UITabBarControllerDelegate` – Leo Dabus Jan 19 '18 at 00:49
@rmaddy Out of sheer curiosity, what exactly am I accessing when doing `tabBarController?`... what is injected there? – Phil Jan 19 '18 at 02:13
1

`UIViewController` provides the `tabBarController` property as a convenience so any view controller embedded in a tab bar controller can its parent tab bar controller. Since `UITabBarController` extends `UIViewController` is also has this property. In fact, if you embed a tab controller inside another tab controller, the child tab controller can use its `tabBarController` property to get the parent tab controller. In your case You are subclassing `UITabBarController` and you want to access `self`, not any parent tab controller. – rmaddy Jan 19 '18 at 03:39

score 0 · Answer 2 · answered Jan 19 '18 at 01:21

0

To detect the item selected event, you have to override didSelect method.

override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
    print("Should go here...")
}

answered Jan 19 '18 at 01:21

Hades0103

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6

1

This is called AFTER the new UIView is displayed. The OP wants to make the shouldSelect method get called so he can do something BEFORE the new UIView is displayed. – David Rector Nov 19 '18 at 22:21

score 0 · Answer 3 · answered Feb 07 '21 at 14:28

0

The right method to implement is DidSelect.....

answered Feb 07 '21 at 14:28

Leandro Diaz

1
2

shouldSelect method of UITabBarControllerDelegate never invoked

3 Answers3