以编程方式在Swift中使用UISlider更改UILabel

Question

我正在学习Swift并尝试使用Slider以编程方式更改Label值。我在func中收到错误，说paybackLabel是一个未解析的标识符。该怎么做？

proto.createdCallback = function() {

    let root = this.createShadowRoot();

    root.innerHTML = "<input id='input' type='text'>"
        + "<br>"
        + "Result: <span id='result'></span>"
        + "<br><button onclick='this.parentNode.process()'>Run</button>";

    this.shadowRoot.process = function() {
        let spanEle = this.querySelector('span');
        let inputEle = this.querySelector('input');
        spanEle.textContent = performAlgorithm(inputEle.value.split(','));
    };
};
document.registerElement('custom-ele', { prototype: proto });

Answer 1

正如我在此建议的那样纠正你的代码。

1。）为Outside公开定义两个变量以公开访问和修改标签值

var paybackLabel : UILabel = UILabel()
var paybackSlider : UISlider = UISlider()

2。）将以下代码放在viewDidload（）

中

//Create Label

paybackLabel = UILabel(frame: CGRectMake(10, 20, 100, 41))
paybackLabel.center = CGPointMake(190, 61)
paybackLabel.textAlignment = NSTextAlignment.Center
paybackLabel.font = UIFont(name: paybackLabel.font.fontName, size:10)
paybackLabel.textColor = UIColor.blueColor()
paybackLabel.text = "Hello World"
self.view.addSubview(paybackLabel)

//Create Slider

paybackSlider = UISlider(frame: CGRectMake (45,70,310,31))
paybackSlider.minimumValue = 0
paybackSlider.maximumValue = 1000
paybackSlider.continuous = true
paybackSlider.tintColor = UIColor.blueColor()
paybackSlider.value = 500
paybackSlider.addTarget(self, action: "paybackSliderValueDidChange:",forControlEvents: .ValueChanged)
paybackLabel.text = "\(paybackSlider.value)"
self.view.addSubview(paybackSlider)

3。）不要通过更改slidervaluechanged事件

来放置在标签上显示值的更改功能

func paybackSliderValueDidChange(sender: UISlider!)
{
    print("payback value: \(sender.value)")
    paybackLabel.text = "\(sender.value)"
}

结果：

现在它的工作很好享受..

Answer 2

在ViewDidLoad（）

之外全局声明

     var  paybackLabel = UILabel()
     var paybackSlider = UISlider()

并且不要忘记将userInteractionEnabled设置为true

   paybackLabel.userInteractionEnabled = true
    paybackSlider.userInteractionEnabled = true