Swift 5 UIButton title didn't change

Question

I just learned Swift and developed an iOS project.

But the button title doesn't change when I click it. How can I change the title?

Simulator: iPhone 11 iOS14.4

This is the code:

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var helloButton: UIButton!
    
    @IBAction func showAlert(_ sender: Any) {
    //var alert = UIAlertController(title: "Hello!", message: "Hello, world!",preferredStyle: UIAlertControllerStyle.Alert)
    let alert = UIAlertController(title: "Hello", message: "Hello, world", preferredStyle: UIAlertController.Style.alert)
        
    alert.addAction(UIAlertAction(title: "close", style: UIAlertAction.Style.default, handler: nil))
        
    self.present(alert,animated:true,completion:nil)
    // ❌ it didn't work
    self.helloButton.setTitle("Clicked",for:.normal)     
    }
    
    override func viewDidLoad() {
      super.viewDidLoad()
    }
}

Answer 1

I found the reason!

It was because the UIButton title being 【Attributed】 or 【Plain】.

✅Different attribute has different API to change the title

If it is 【Attributed】: We should change the UIButton title by:

//
//  ViewController.swift
//  HelloCocoa
//
//  Created by LearnChild on 2021/4/14.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var helloButton: UIButton!
    
    
    @IBAction func showAlert(_ sender: Any) {
//        var alert = UIAlertController(title: "Hello!", message: "Hello, world!",preferredStyle: UIAlertControllerStyle.Alert)
        let alert = UIAlertController(title: "Hello", message: "Hello, world", preferredStyle: UIAlertController.Style.alert)

        alert.addAction(UIAlertAction(title: "close", style: UIAlertAction.Style.default, handler: nil))

        self.present(alert,animated:true,completion:nil)

        //        if UIButton title is Plain
//        self.helloButton.setTitle("Clicked",for:.normal)
        
        
        
//        if UIButton title is Attributed✅👇
        let myNormalAttributedTitle = NSAttributedString(string: "Click Here",
                                                         attributes: [NSAttributedString.Key.foregroundColor : UIColor.blue])
        self.helloButton.setAttributedTitle(myNormalAttributedTitle,for:.normal)


    }

    
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }


}

And if it's 【Plain】:

//
//  ViewController.swift
//  HelloCocoa
//
//  Created by LearnChild on 2021/4/14.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var helloButton: UIButton!
    
    
    @IBAction func showAlert(_ sender: Any) {
//        var alert = UIAlertController(title: "Hello!", message: "Hello, world!",preferredStyle: UIAlertControllerStyle.Alert)
        let alert = UIAlertController(title: "Hello", message: "Hello, world", preferredStyle: UIAlertController.Style.alert)

        alert.addAction(UIAlertAction(title: "close", style: UIAlertAction.Style.default, handler: nil))

        self.present(alert,animated:true,completion:nil)

        //        if UIButton title is Plain✅👇
        self.helloButton.setTitle("Clicked",for:.normal)
        
        
        
//        if UIButton title is Attributed✅
//        let myNormalAttributedTitle = NSAttributedString(string: "Click Here",
//                                                         attributes: [NSAttributedString.Key.foregroundColor : UIColor.blue])
//        self.helloButton.setAttributedTitle(myNormalAttributedTitle,for:.normal)


    }

    

    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }


}

Thanks to everyone who helped!