[英]Programmatically Change UILabel with UISlider in Swift
我正在學習Swift並嘗試使用Slider以編程方式更改Label值。 我在func中收到錯誤,說paybackLabel是一個未解析的標識符。 該怎么做?
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
//Create Label
let paybackLabel = UILabel(frame: CGRectMake(0, 0, 300, 41))
paybackLabel.center = CGPointMake(190, 284)
paybackLabel.textAlignment = NSTextAlignment.Center
paybackLabel.font = UIFont(name: paybackLabel.font.fontName, size: 40)
paybackLabel.textColor = UIColor.whiteColor()
paybackLabel.text = "Hello World"
self.view.addSubview(paybackLabel)
//Create Slider
let paybackSlider = UISlider(frame: CGRectMake (45,546,310,31))
paybackSlider.minimumValue = 0
paybackSlider.maximumValue = 1000
paybackSlider.continuous = true
paybackSlider.tintColor = UIColor.blueColor()
paybackSlider.value = 500
paybackSlider.addTarget(self, action: "paybackSliderValueDidChange:",forControlEvents: .ValueChanged)
self.view.addSubview(paybackSlider)
}
func paybackSliderValueDidChange(sender: UISlider!)
{
print("payback value: \(sender.value)")
paybackLabel.text = "\(sender.value)"
}
}
正如我在這里建議的那樣糾正你的代碼。
1.)為Outside定義兩個變量以公開訪問和修改標簽值
var paybackLabel : UILabel = UILabel()
var paybackSlider : UISlider = UISlider()
2.)將以下代碼放在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.)不要通過更改slidervaluechanged事件來放置在標簽上顯示值的更改功能
func paybackSliderValueDidChange(sender: UISlider!)
{
print("payback value: \(sender.value)")
paybackLabel.text = "\(sender.value)"
}
結果:
它的工作很好享受..
在ViewDidLoad()之外全局聲明
var paybackLabel = UILabel()
var paybackSlider = UISlider()
並且不要忘記將userInteractionEnabled設置為true
paybackLabel.userInteractionEnabled = true
paybackSlider.userInteractionEnabled = true
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