为什么选择按钮时按钮背景变为蓝色？

Question

I have three buttons, when selected they change background color to red - yet a blue background is popping up as well and I can't figure out why (sorry if the reason is obvious, ive only been doing "programming" for 3 weeks. I can't find anything in the code that would explain itI have three buttons, when selected they change background color to red - yet a blue background is popping up as well and I can't figure out why (sorry if the原因很明显，我只做了 3 周的“编程”。我在代码中找不到任何可以解释它的东西

[enter image description here][1]import UIKit

class ViewController: UIViewController {

var counterEN : Int = 0
var count = Array(1...150).filter { $0 % 1 != 0}.count
var pizzaCount = 0


@IBOutlet weak var pizzaCounter: UILabel!
@IBOutlet weak var textField: UITextField!
@IBAction func test(_ sender: UIButton) {
    self.textField.text = sender.currentTitle
}

var lastY: CGFloat = 100

override func viewDidLoad() {
    super.viewDidLoad()
}

@IBAction func buttonClicked(_ sender: UIButton) {
    pizzaCount = pizzaCount + 1
    pizzaCounter.text = ("Antal pizza: ") + "\(pizzaCount)"
    let contentView = UIView()
    addViewsTo(contentView, title: sender.currentTitle)
    contentView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(contentView)


    // Add size constraints to the content view (260, 30)
    NSLayoutConstraint(item: contentView, attribute: .width, relatedBy: .equal,
                       toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant:                       850.0).isActive = true
    NSLayoutConstraint(item: contentView, attribute: .height, relatedBy: .equal,
                       toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant:   `       30.0).isActive = true
    // Add position constraints to the content view (horizontal center, 100 from the top)
    NSLayoutConstraint(item: contentView, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1.0, constant: lastY).isActive = true
    NSLayoutConstraint(item: contentView, attribute: .centerX, relatedBy: .equal, toItem:    view, attribute: .centerX, multiplier: 1.0, constant: 0.0).isActive = true

    // Update last Y position to have the gaps between views to be 10
    lastY += 50
}

    // Add label and button to the content view
    func addViewsTo(_ contentView: UIView, title: String?) {
    // Add a label with size of (100, 30)
    let label = UILabel()
    label.text = title
    //label.text = ("1 x 17 ")

    label.frame = CGRect(x: 0.0, y: 0.0, width: 100.0, height: 30.0)
    contentView.addSubview(label)



    let DressingButton = UIButton(type: .system)

    DressingButton.frame = CGRect(x: 210, y: 0, width: 40, height: 30)
    DressingButton.setTitle("D", for: .normal)
    DressingButton.setTitleColor(.black, for: .normal)

    DressingButton.setTitleColor(.red, for: .selected)
    DressingButton.sendActions(for: .touchUpInside)
    contentView.addSubview(DressingButton)

    DressingButton.addTarget(self, action: #selector(dressingAction(_:)), for .touchUpInside)


    let Chili = UIButton(type: .system)

    Chili.frame = CGRect(x: 160, y: 0, width: 40, height: 30)
    Chili.setTitle("C", for: .normal)
    Chili.setTitleColor(.black, for: .normal)
    Chili.backgroundColor = UIColor.white
    Chili.setTitleColor(.systemRed, for: .selected)
    Chili.sendActions(for: .touchUpInside)
    contentView.addSubview(Chili)


    Chili.addTarget(self, action: #selector(dressingAction(_:)), for: .touchUpInside)

    let Hvidløg = UIButton(type: .system)

    Hvidløg.frame = CGRect(x: 110, y: 0, width: 40, height: 30)
    Hvidløg.setTitle("H", for: .normal)
    Hvidløg.setTitleColor(.black, for: .normal)
    Hvidløg.setTitleColor(.red, for: .selected)
    Hvidløg.backgroundColor = UIColor.white

    Hvidløg.sendActions(for: .touchUpInside)


    contentView.addSubview(Hvidløg)

    Hvidløg.addTarget(self, action: #selector(dressingAction(_:)), for: .touchUpInside)


    let button2 = UIButton(type: .system)

    button2.frame = CGRect(x: -40, y: 20, width: 150, height: 30)
    button2.setTitle("Alm", for: .normal)
    button2.setTitle("Ful", for: .selected)
    button2.setTitle("Glu", for: .selected)
    // Set button action
    button2.addTarget(self, action: #selector(buttonAction(_:)), for: .touchUpInside)

    contentView.addSubview(button2)
    self.view = view
    }
    @objc func dressingAction(_ sender:UIButton){

    sender.isSelected.toggle()
    print("knap")
    sender.backgroundColor = UIColor.red
    }

    @objc func buttonAction(_ sender:UIButton!)
    {

    sender.isSelected = !sender.isSelected
    sender.setTitle("Alm", for: .normal)

    if sender.isSelected{
        sender.setTitle("Fuld", for: .selected)}
    else {
        sender.setTitle("Glu", for: .selected)
        sender.isSelected = !sender.isSelected
 //          sender.tintColor = .clear

////        if sender.isSelected{
//          sender.setTitleColor(.green, for: .selected)
//            }
//            else{
//          sender.setTitleColor(.blue, for: .selected)
//
        func buttonAction(_ button3:UIButton!) {

        print("Button tapped"); counterEN += 1; count += 1; print (counterEN); print (count)

            }

        }
    }
  }

Answer 1

请将您的按钮类型更改为 .custom，问题将得到解决。

let dressingButton = UIButton(type: .custom)

Answer 2

尝试将您的按钮类型更改为自定义