[Swift] How to display when the quiz app answers correctly [Beginner]

Introduction

I didn't know how to display it when I answered correctly with the quiz app, so I looked it up and summarized it.

I have no practical experience and am studying Swift by myself. I would like to output what I have learned. As a beginner, there may be mistakes. At that time, I would appreciate it if you could tell me.

environment

macOS Catalina10.15.4 Xcode11.7

Completion drawing

Set the screen as shown in the image below on the story board

Connect the code with UIImage and UIButton.

 @IBOutlet weak var answerBtn1: UIButton!
 @IBOutlet weak var answerBtn2: UIButton!
 @IBOutlet weak var answerBtn3: UIButton!
 @IBOutlet weak var answerBtn4: UIButton!
    
 @IBOutlet weak var maruImageView: UIImageView!

UIButton also connects with @IBAction

 @IBAction func answerBtn1Action(_ sender: Any) {
    }
    

    @IBAction func answerBtn2Action(_ sender: Any) {
        //I will not use it this time, but originally write the process here
    }
    
    
    @IBAction func answerBtn3Action(_ sender: Any) {
        //I will not use it this time, but originally write the process here
    }
    
    @IBAction func answerBtn4Action(_ sender: Any) {
        //I will not use it this time, but originally write the process here

    }

○ Store images (maru.png)

Processing when the answer is correct

1, ○ Display image

Write the code inside answerBtn1Action

//○ Display the image
maruImageView.image = UIImage(named: "maru.png ")
//○ Restore the transmittance of the image. When you press the button from the second time onward, if you do not write this, the image will remain transparent.
maruImageView.alpha = 1.0

2. When the answer is correct, make the button color blue

answerBtn1.backgroundColor = .blue

After 3 or 1 seconds, erase the ○ image and the button color.

At this time, use the UIView animation.

//UIView.Color returns after 1 second using animate function
 UIView.animate(withDuration: 1.0) {
      //Change button color to systemOrenge
      self.answerBtn1.backgroundColor = .systemOrange
      //○ Set the transmittance of the image to zero. Zero and transparent.
      self.maruImageView.alpha = .zero
}

Full code

import UIKit

class ViewController: UIViewController {
    
    @IBOutlet weak var answerBtn1: UIButton!
    @IBOutlet weak var answerBtn2: UIButton!
    @IBOutlet weak var answerBtn3: UIButton!
    @IBOutlet weak var answerBtn4: UIButton!
    
    @IBOutlet weak var maruImageView: UIImageView!
    
    

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

    //Processing when the answer is correct
    @IBAction func answerBtn1Action(_ sender: Any) {
        print("Correct answer")
        answerBtn1.backgroundColor = .blue
        //○ Display image
        maruImageView.image = UIImage(named: "maru.png ")
        //○ Restore the transmittance of the image
        maruImageView.alpha = 1.0
        
        //UIView.Color returns after 1 second using animate function
        UIView.animate(withDuration: 1.0) {
            //Change button color to systemOrenge
            self.answerBtn1.backgroundColor = .systemOrange
            //○ Set the transmittance of the image to zero. Zero and transparent.
            self.maruImageView.alpha = .zero
        }
    }
    
    
    @IBAction func answerBtn2Action(_ sender: Any) {
        //I will not use it this time, but originally write the process here
    }
    
    
    @IBAction func answerBtn3Action(_ sender: Any) {
        //I will not use it this time, but originally write the process here
    }
    
    @IBAction func answerBtn4Action(_ sender: Any) {
        //I will not use it this time, but originally write the process here

    }
    
}

Reference site

https://qiita.com/hachinobu/items/57d4c305c907805b4a53