在 Swift 3 中进入背景后,viewDidAppear 中的动画无法正常工作
Animation in viewDidAppear not working after going background in Swift 3
我目前正在开发一个倒计时应用程序 Swift 3.在柜台后面,我创建了一个圆圈,它根据计数器进行动画处理。
我的问题很简单:当我点击主页并将应用程序置于后台时,当我返回应用程序时动画不再工作。我不知道为什么。有趣的事实:"drawing" 是一个普通的圆圈,只有边框是动画的。圆圈的背景还是可以的,就是边框动画不行了
这是我的代码:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let screen = self.view.frame.size.width
let y = CGFloat(190)
let circleWidth = CGFloat(200)
let circleHeight = circleWidth
// Create a new CircleView
let circleView = CircleView(frame: CGRect(x: (screen/2) - (circleWidth/2), y: y, width: circleWidth, height: circleHeight))
view.addSubview(circleView)
// Animate the drawing of the circle over the course of 1 second
circleView.animateCircle(TimeInterval(seconds))
}
CircleView class:
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: CGFloat(-M_PI/2), endAngle: CGFloat(M_PI*1.5), clockwise: true)
// Setup the CAShapeLayer with the path, colors, and line width
circleLayer = CAShapeLayer()
circleLayer.path = circlePath.cgPath
circleLayer.fillColor = UIColor(red: 255/255, green: 255/255, blue: 255/255, alpha: 0.2).cgColor
circleLayer.strokeColor = UIColor(red: 165/255, green: 219/255, blue: 255/255, alpha: 0.8).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")
}
}
您需要做的就是在动画代码中再添加一行:
animation.isRemovedOnCompletion = false
您的代码将是:
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)
animation.isRemovedOnCompletion = false
// 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")
}
我目前正在开发一个倒计时应用程序 Swift 3.在柜台后面,我创建了一个圆圈,它根据计数器进行动画处理。
我的问题很简单:当我点击主页并将应用程序置于后台时,当我返回应用程序时动画不再工作。我不知道为什么。有趣的事实:"drawing" 是一个普通的圆圈,只有边框是动画的。圆圈的背景还是可以的,就是边框动画不行了
这是我的代码:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let screen = self.view.frame.size.width
let y = CGFloat(190)
let circleWidth = CGFloat(200)
let circleHeight = circleWidth
// Create a new CircleView
let circleView = CircleView(frame: CGRect(x: (screen/2) - (circleWidth/2), y: y, width: circleWidth, height: circleHeight))
view.addSubview(circleView)
// Animate the drawing of the circle over the course of 1 second
circleView.animateCircle(TimeInterval(seconds))
}
CircleView class:
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: CGFloat(-M_PI/2), endAngle: CGFloat(M_PI*1.5), clockwise: true)
// Setup the CAShapeLayer with the path, colors, and line width
circleLayer = CAShapeLayer()
circleLayer.path = circlePath.cgPath
circleLayer.fillColor = UIColor(red: 255/255, green: 255/255, blue: 255/255, alpha: 0.2).cgColor
circleLayer.strokeColor = UIColor(red: 165/255, green: 219/255, blue: 255/255, alpha: 0.8).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")
}
}
您需要做的就是在动画代码中再添加一行:
animation.isRemovedOnCompletion = false
您的代码将是:
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)
animation.isRemovedOnCompletion = false
// 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")
}