在 Swift 中使用 IBAction 但不使用 viewDidLoad 的函数

Question

我想在我的项目中添加一个圆形动画。我找到 very good help here.

此代码适用于我的主页 viewDidLoad，但不适用于其他页面。但是，如果我在所需页面上放置一个测试按钮，它就会起作用。当我调用viewDidLoad中的函数时，动画已经结束了，即使我放10秒或60秒。

这是代码：

import Foundation
import UIKit

class CircleView: UIView{
   var circleLayer: CAShapeLayer!
   
   override init(frame: CGRect) {
      super.init(frame: frame)
      self.backgroundColor = UIColor.clear
      
      // Use UIBezierPath as an easy way to create the CGPath for the layer.
      // The path should be the entire circle.
      let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(M_PI * 2.0), clockwise: true)
      
      // Setup the CAShapeLayer with the path, colors, and line width
      circleLayer = CAShapeLayer()
      circleLayer.path = circlePath.cgPath
      circleLayer.fillColor = UIColor.clear.cgColor
      circleLayer.strokeColor = UIColor.white.cgColor
      circleLayer.lineWidth = 2.0;
      
      // Don't draw the circle initially
      circleLayer.strokeEnd = 0.0
      
      // Add the circleLayer to the view's layer's sublayers
      layer.addSublayer(circleLayer)
   }
   
   required init?(coder aDecoder: NSCoder) {
      fatalError("init(coder:) has not been implemented")
   }

   
   func animateCircle(_ duration: TimeInterval) {
      // We want to animate the strokeEnd property of the circleLayer
      let animation = CABasicAnimation(keyPath: "strokeEnd")
      
      // Set the animation duration appropriately
      animation.duration = duration
      
      // Animate from 0 (no circle) to 1 (full circle)
      animation.fromValue = 1
      animation.toValue = 0
      
      // Do a linear animation (i.e. the speed of the animation stays the same)
      animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
      
      // Set the circleLayer's strokeEnd property to 1.0 now so that it's the
      // right value when the animation ends.
      circleLayer.strokeEnd = 0.0
      
      // Do the actual animation
      circleLayer.add(animation, forKey: "animateCircle")
   }
   
}

在我看来：

func addCircleView() {
      let diceRoll = CGFloat(100)
      let circleWidth = CGFloat(200)
      let circleHeight = circleWidth
      
      // Create a new CircleView
      let circleView = CircleView(frame: CGRect(diceRoll, 0, circleWidth, circleHeight))
      
      view.addSubview(circleView)
      
      // Animate the drawing of the circle over the course of 1 second
      circleView.animateCircle(TimeInterval(seconds))
   }

(seconds 是一个实例变量，我想在视图打开时调用 addCircleView)。

Answer 1

viewDidLoad 在实例化 UIViewController 时被调用。显示 UIViewController 时调用 viewDidAppear。您需要将动画移动到 viewDidAppear

在 Swift 中使用 IBAction 但不使用 viewDidLoad 的函数

Function working with IBAction but not with viewDidLoad in Swift

animation

geometry

viewdidload

swift

swift3