如何随分段控件切换自动更改按钮文本

Hey there! Let's get this sorted so your button updates automatically whenever the segmented control switches—no more relying on button taps to change the text. Here's a straightforward approach:

Step 1: Hook up the segmented control's value change event #

First, we need to listen for when the user switches between the "Log In" and "Sign In" segments. How you do this depends on whether you built your UI in Storyboard/XIB or code:

If using Storyboard/XIB:

• Open your Storyboard, find the UISegmentedControl, right-click and drag it to your ViewController class file.
• In the pop-up menu, select Action, name the method something like segmentedControlDidChange, set the type to UISegmentedControl, and choose the Value Changed event.

If creating the segmented control in code:

Add this when setting up your segmented control to link it to a handler method:

let authSegmentedControl = UISegmentedControl(items: ["Log In", "Sign In"])
authSegmentedControl.addTarget(self, action: #selector(segmentedControlDidChange(_:)), for: .valueChanged)
// Don't forget to add it to your view and set constraints if needed
view.addSubview(authSegmentedControl)

Step 2: Update the button title in the handler method #

Now write the method that will update your button's title based on the selected segment:

@objc func segmentedControlDidChange(_ sender: UISegmentedControl) {
    switch sender.selectedSegmentIndex {
    case 0:
        // Selected "Log In" segment
        actionButton.setTitle("Log In", for: .normal)
    case 1:
        // Selected "Sign In" segment
        actionButton.setTitle("Sign In", for: .normal)
    default:
        // Fallback in case of unexpected index (optional)
        actionButton.setTitle("Log In", for: .normal)
    }
}

Step 3: Set the initial button title #

Make sure the button starts with the correct text matching the segmented control's default selected state. Add this to viewDidLoad:

override func viewDidLoad() {
    super.viewDidLoad()
    // Match the default selected segment (index 0 = "Log In" here)
    actionButton.setTitle("Log In", for: .normal)
}

That's it! Now whenever the user toggles the segmented control, the button's title will automatically update to match the active segment—no extra button taps required.

内容的提问来源于stack exchange，提问作者Peter Brink