最近擼了一個上拉重新整理的小輪子，只要遵循一個協議就能自定義自己動效的上拉重新整理和載入，我自己也寫了幾個動效進去，下面是一個比較好的動效的實現過程
先上效果圖和github地址，歡迎歡迎star，完整程式碼個demo和進入檢視，有其他好的動效大家也可以學習交流~
分析動效
寫一個動效的第一步就應該仔細的去分析它，把它的每一幀展開來看，找一個最合適的方式來實現它，我們可以把以上動畫分解成以下三個步驟：
- 箭頭的繪製和動效
- 圓環的繪製和小點的旋轉
- 對勾的繪製和動畫
以下是會用到主要的類：
CAShapeLayerUIBezierPathCABasicAnimationCAKeyframeAnimationDispatchSourceTimer
箭頭的繪製和動效
剪頭的繪製我們用CAShapeLayer配合UIBezierPath來實現，把箭頭分解成兩個部分，一個是垂直的線和箭頭頭的部分，方便實現之後的動畫效果，下面是繪製主要的程式碼和效果圖：
// 繪製垂直的線
private func initLineLayer() {
let width = frame.size.width
let height = frame.size.height
let path = UIBezierPath()
path.move(to: .init(x: width/2, y: 0))
path.addLine(to: .init(x: width/2, y: height/2 + height/3))
lineLayer = CAShapeLayer()
lineLayer?.lineWidth = lineWidth*2
lineLayer?.strokeColor = color.cgColor
lineLayer?.fillColor = UIColor.clear.cgColor
lineLayer?.lineCap = kCALineCapRound
lineLayer?.path = path.cgPath
lineLayer?.strokeStart = 0.5
addSublayer(lineLayer!)
}
// 繪製箭頭的頭部
private func initArrowLayer() {
let width = frame.size.width
let height = frame.size.height
let path = UIBezierPath()
path.move(to: .init(x: width/2 - height/6, y: height/2 + height/6))
path.addLine(to: .init(x: width/2, y: height/2 + height/3))
path.addLine(to: .init(x: width/2 + height/6, y: height/2 + height/6))
arrowLayer = CAShapeLayer()
arrowLayer?.lineWidth = lineWidth*2
arrowLayer?.strokeColor = color.cgColor
arrowLayer?.lineCap = kCALineCapRound
arrowLayer?.lineJoin = kCALineJoinRound
arrowLayer?.fillColor = UIColor.clear.cgColor
arrowLayer?.path = path.cgPath
addSublayer(arrowLayer!)
}複製程式碼然後是箭頭動畫實現，我們分別對線和箭頭頭部進行動畫，通過CABasicAnimation對它們的strokeStart和strokeEnd進行控制來實現動畫，下面是效果圖和主要程式碼：
// 箭頭的動畫
public func startAnimation() -> Self {
let start = CABasicAnimation(keyPath: "strokeStart")
start.duration = animationDuration
start.fromValue = 0
start.toValue = 0.5
start.isRemovedOnCompletion = false
start.fillMode = kCAFillModeForwards
start.delegate = self
start.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
let end = CABasicAnimation(keyPath: "strokeEnd")
end.duration = animationDuration
end.fromValue = 1
end.toValue = 0.5
end.isRemovedOnCompletion = false
end.fillMode = kCAFillModeForwards
end.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
arrowLayer?.add(start, forKey: "strokeStart")
arrowLayer?.add(end, forKey: "strokeEnd")
return self
}
// 線的動畫
private func addLineAnimation() {
let start = CABasicAnimation(keyPath: "strokeStart")
start.fromValue = 0.5
start.toValue = 0
start.isRemovedOnCompletion = false
start.fillMode = kCAFillModeForwards
start.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
start.duration = animationDuration/2
lineLayer?.add(start, forKey: "strokeStart")
let end = CABasicAnimation(keyPath: "strokeEnd")
end.beginTime = CACurrentMediaTime() + animationDuration/3
end.duration = animationDuration/2
end.fromValue = 1
end.toValue = 0.03
end.isRemovedOnCompletion = false
end.fillMode = kCAFillModeForwards
end.delegate = self
end.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
lineLayer?.add(end, forKey: "strokeEnd")
}
// 通過delegate控制順序
func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
if flag {
if let anim = anim as? CABasicAnimation {
if anim.keyPath == "strokeStart" {
arrowLayer?.isHidden = true
addLineAnimation()
}else {
lineLayer?.isHidden = true
animationEnd?()
}
}
}
}複製程式碼圓環的繪製和小點的旋轉
同樣的圓環和小點的繪製我們也可以用CAShapeLayer配合UIBezierPath來實現
，下面是效果圖和主要程式碼：
// 繪製外環
private func drawCircle() {
let width = frame.size.width
let height = frame.size.height
let path = UIBezierPath()
path.addArc(withCenter: .init(x: width/2, y: height/2), radius: height/2, startAngle: 0, endAngle: CGFloat(Double.pi * 2.0), clockwise: false)
circle.lineWidth = lineWidth
circle.strokeColor = color.cgColor
circle.fillColor = UIColor.clear.cgColor
circle.path = path.cgPath
addSublayer(circle)
circle.isHidden = true
}
// 繪製小點
private func drawPoint() {
let width = frame.size.width
let path = UIBezierPath()
path.addArc(withCenter: .init(x: width/2, y: width/2), radius: width/2, startAngle: CGFloat(Double.pi * 1.5), endAngle: CGFloat((Double.pi * 1.5) - 0.1), clockwise: false)
point.lineCap = kCALineCapRound
point.lineWidth = lineWidth*2
point.fillColor = UIColor.clear.cgColor
point.strokeColor = pointColor.cgColor
point.path = path.cgPath
pointBack.addSublayer(point)
point.isHidden = true
}複製程式碼旋轉的實現，因為旋轉的速度是有個加速的效果的，所以我們使用DispatchSourceTimer來控制選擇的速度，下面是效果圖和主要程式碼：
// 旋轉的控制
public func startAnimation() {
circle.isHidden = false
point.isHidden = false
codeTimer = DispatchSource.makeTimerSource(queue: DispatchQueue.global())
codeTimer?.scheduleRepeating(deadline: .now(), interval: .milliseconds(42))
codeTimer?.setEventHandler(handler: { [weak self] in
guard self != nil else {
return
}
self!.rotated = self!.rotated - self!.rotatedSpeed
if self!.stop {
let count = Int(self!.rotated / CGFloat(Double.pi * 2))
if (CGFloat(Double.pi * 2 * Double(count)) - self!.rotated) >= 1.1 {
var transform = CGAffineTransform.identity
transform = transform.rotated(by: -1.1)
DispatchQueue.main.async {
self!.pointBack.setAffineTransform(transform)
self!.point.isHidden = true
self!.check?.startAnimation()
}
self!.codeTimer?.cancel()
return
}
}
if self!.rotatedSpeed < 0.65 {
if self!.speedInterval < 0.02 {
self!.speedInterval = self!.speedInterval + 0.001
}
self!.rotatedSpeed = self!.rotatedSpeed + self!.speedInterval
}
var transform = CGAffineTransform.identity
transform = transform.rotated(by: self!.rotated)
DispatchQueue.main.async {
self!.pointBack.setAffineTransform(transform)
}
})
codeTimer?.resume()
addPointAnimation()
}
// 點的變化
private func addPointAnimation() {
let width = frame.size.width
let path = CABasicAnimation(keyPath: "path")
path.beginTime = CACurrentMediaTime() + 1
path.fromValue = point.path
let toPath = UIBezierPath()
toPath.addArc(withCenter: .init(x: width/2, y: width/2), radius: width/2, startAngle: CGFloat(Double.pi * 1.5), endAngle: CGFloat((Double.pi * 1.5) - 0.3), clockwise: false)
path.toValue = toPath.cgPath
path.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
path.duration = 2
path.isRemovedOnCompletion = false
path.fillMode = kCAFillModeForwards
point.add(path, forKey: "path")
}複製程式碼對勾的繪製和動畫
對勾的繪製我們也是用CAShapeLayer配合UIBezierPath來繪製，下面是效果圖和主要的程式碼：
// 繪製對號
private func drawCheck() {
let width = Double(frame.size.width)
check = CAShapeLayer()
check?.lineCap = kCALineCapRound
check?.lineJoin = kCALineJoinRound
check?.lineWidth = lineWidth
check?.fillColor = UIColor.clear.cgColor
check?.strokeColor = color.cgColor
check?.strokeStart = 0
check?.strokeEnd = 0
let path = UIBezierPath()
let a = sin(0.4) * (width/2)
let b = cos(0.4) * (width/2)
path.move(to: CGPoint.init(x: width/2 - b, y: width/2 - a))
path.addLine(to: CGPoint.init(x: width/2 - width/20 , y: width/2 + width/8))
path.addLine(to: CGPoint.init(x: width - width/5, y: width/2 - a))
check?.path = path.cgPath
addSublayer(check!)
}複製程式碼對勾的動畫我們通過CAKeyframeAnimation來控制對勾的strokeStart和strokeEnd來實現對勾的動畫，下面是效果圖和主要程式碼：
// 對勾的動畫
func startAnimation() {
let start = CAKeyframeAnimation(keyPath: "strokeStart")
start.values = [0, 0.4, 0.3]
start.isRemovedOnCompletion = false
start.fillMode = kCAFillModeForwards
start.duration = 0.2
start.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
let end = CAKeyframeAnimation(keyPath: "strokeEnd")
end.values = [0, 1, 0.9]
end.isRemovedOnCompletion = false
end.fillMode = kCAFillModeForwards
end.duration = 0.3
end.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
check?.add(start, forKey: "start")
check?.add(end, forKey: "end")
}複製程式碼總結
關於小球的旋轉我沒有選擇CADisplayLink而是選擇的DispatchSourceTimer，是因為CADisplayLink會受到UITableview的影響，關於動畫的實現需要耐心去調細節，實現方式也各種各樣，大家如果有什麼更好的建議或者建議大家可以提出來~
完整的程式碼，大家可以去github地址去下載，歡迎大家star和發表意見和貢獻程式碼，有好的動效的話也可以提供，最後謝謝大家的閱讀