Question

我有以下UICollectionViewCell子类，我在没有使用故事板的情况下创建了UISlider：

class ProductDetailPersonalLoanViewCell: UICollectionViewCell {
    let valueSlider: UISlider = {
        let mySlider = UISlider(frame:CGRect(x: 10, y: 100, width: 300, height: 20))
        mySlider.isUserInteractionEnabled = true
        mySlider.minimumValue = 0
        mySlider.maximumValue = 100
        mySlider.isContinuous = true
        mySlider.tintColor = UIColor.green
        mySlider.addTarget(self, action: #selector(sliderValueDidChange(_:)), for: .valueChanged)


        return mySlider
    }()

    override init(frame: CGRect){
        super.init(frame: frame)

        setupViews()
    }

    func setupViews(){
        addSubview(valueSlider)

        // ....... layout constraints
    }

    func sliderValueDidChange(_ sender:UISlider!){
        print("Slider value changed")
        let roundedStepValue = round(sender.value / step) * step
        sender.value = roundedStepValue

        print("Slider step value \(Int(roundedStepValue))")
    }

}

问题在于，由于某种原因，当我移动拇指时没有触发事件，所以我无法使用UISlider值。有人知道如何解决这个问题吗？

Answer 1

您必须在计算值块之外的valueSlider添加目标：

 let valueSlider: UISlider = {
    let mySlider = UISlider(frame:CGRect(x: 10, y: 100, width: 300, height: 20))
    mySlider.isUserInteractionEnabled = true
    mySlider.minimumValue = 0
    mySlider.maximumValue = 100
    mySlider.isContinuous = true
    mySlider.tintColor = UIColor.green

    return mySlider
}()

override init(frame: CGRect){
    super.init(frame: frame)

    setupViews()
    valueSlider.addTarget(self, action: #selector(sliderValueDidChange(_:)), for: .valueChanged)
}

或者，我认为这是一个更好的解决方案，将计算值更改为惰性属性：

lazy var valueSlider: UISlider = {
    let mySlider = UISlider(frame:CGRect(x: 10, y: 100, width: 300, height: 20))
    mySlider.isUserInteractionEnabled = true
    mySlider.minimumValue = 0
    mySlider.maximumValue = 100
    mySlider.isContinuous = true
    mySlider.tintColor = UIColor.green
    mySlider.addTarget(self, action: #selector(sliderValueDidChange(_:)), for: .valueChanged)

    return mySlider
}()

override init(frame: CGRect){
    super.init(frame: frame)

    setupViews()

}

在Swift 3中以编程方式创建的UISlider中未触发事件

1 个答案: