Question

我以编程方式添加了水平UIScrollView中的多个按钮。我必须更改用户所选按钮的颜色。但是，如果用户选择另一个按钮，则必须将前一个按钮颜色更改为默认颜色。我怎样才能做到这一点？请帮帮我......

func createHorizontalScroll()
{
    let scrollView = UIScrollView(frame: CGRect(x: CGFloat(0), y: CGFloat(410), width: CGFloat(view.frame.size.width), height: CGFloat(40)))

    var buttonX: CGFloat = 0

    for index in 0..<btnNames.count
    {
        //add an element and the previous element together
        let sum = btnNames[index]

        button = UIButton(frame: CGRect(x: CGFloat(buttonX), y: CGFloat(0), width: CGFloat(100), height: CGFloat(40)))

        print("btnNames:\(sum)")

        button.setTitle("\(sum)",for:.normal)
        button.layer.borderWidth = 2.5
        button.layer.borderWidth = 2.5
        button.layer.borderColor = UIColor.white.cgColor
        button.layer.backgroundColor = UIColor.black.cgColor
        button.tag = index
        scrollView.addSubview(button)
        buttonX = button.frame.size.width + buttonX

        button.addTarget(self, action: #selector(changeView), for: .touchUpInside)
    }

    scrollView.contentSize = CGSize(width: CGFloat(buttonX), height: CGFloat(scrollView.frame.size.height))
    scrollView.backgroundColor = UIColor.clear
    view.addSubview(scrollView)
}

func changeView(_ sender: UIButton)
{
   print("I Clicked a button \(Int(sender.tag))")
}

Answer 1

由于您已经在使用标签，因此它不应该成为问题。 changeView函数应该像这样工作：

func changeView(_ sender: UIButton)
{
    let scrollView = sender.superview as! UIScrollView //This is mildly hacky - store your scroll view in an instance variable
    for view in scrollView.subviews {
        guard let button = view as? UIButton else {
            continue
        }

        button.backgroundColor = sender.tag == button.tag ? UIColor.red : UIColor.black
    }
}

Answer 2

没有标签的简单解决方案。

声明属性currentButton

weak var currentButton : UIButton?

在changeView重设currentButton的颜色，设置sender的颜色并将sender指定给currentButton。

func changeView(_ sender: UIButton)
{
    currentButton?.backgroundColor = .black
    currentButton = sender
    sender.backgroundColor = .red
}

由于可选链接，如果currentButton为currentButton

，则不会设置nil.的颜色

Answer 3

保留UIButton类型的周属性以暂时保存所选按钮。

weak var selectedButton: UIButton?

在按钮的选择器中，将selectedButton的颜色设为默认值，然后更改新选择按钮的颜色并重置selectedButton

@IBAction func actionTouchUpInside(sender: UIButton) {
    if let selectedButton = self.selectedButton {
        selectedButton.backgroundColor = UIColor.clear
    }

    sender.backgroundColor = UIColor.blue
    selectedButton = sender
}

按下下一个按钮时如何更改上一个按钮颜色？

3 个答案: