Ios 使用UIBezierPath绘制闪烁箭头
我有一个Ios 使用UIBezierPath绘制闪烁箭头,ios,swift,uibezierpath,Ios,Swift,Uibezierpath,我有一个UIScrollView,里面有一个很长的文本。我想告诉用户,它有更多的内容可以阅读。因此,我添加了一个底部带有UIBezierPath的箭头 class ArrowView: UIView { var arrowPath: UIBezierPath! // Only override draw() if you perform custom drawing. // An empty implementation adversely affects perform
UIScrollView
,里面有一个很长的文本。我想告诉用户,它有更多的内容可以阅读。因此,我添加了一个底部带有UIBezierPath
的箭头
class ArrowView: UIView {
var arrowPath: UIBezierPath!
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
// Drawing code
self.drawArrow(from: CGPoint(x: rect.midX, y: rect.minY), to: CGPoint(x: rect.midX, y: rect.maxY),
tailWidth: 10, headWidth: 25, headLength: 20)
//arrowPath.fill()
}
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.darkGray
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
private func drawArrow(from start: CGPoint, to end: CGPoint, tailWidth: CGFloat, headWidth: CGFloat, headLength: CGFloat){
let length = hypot(end.x - start.x, end.y - start.y)
let tailLength = length - headLength
func p(_ x: CGFloat, _ y: CGFloat) -> CGPoint { return CGPoint(x: x, y: y) }
let points: [CGPoint] = [
p(0, tailWidth / 2),
p(tailLength, tailWidth / 2),
p(tailLength, headWidth / 2),
p(length, 0),
p(tailLength, -headWidth / 2),
p(tailLength, -tailWidth / 2),
p(0, -tailWidth / 2)
]
let cosine = (end.x - start.x) / length
let sine = (end.y - start.y) / length
let transform = CGAffineTransform(a: cosine, b: sine, c: -sine, d: cosine, tx: start.x, ty: start.y)
let path = CGMutablePath()
path.addLines(between: points, transform: transform)
path.closeSubpath()
arrowPath = UIBezierPath.init(cgPath: path)
}
}
我的问题:如何实现箭头上的闪烁动画。假设它有一个从白色到蓝色的渐变层。它应该从白色开始到蓝色,然后在开始点看到蓝色,然后在箭头的结束点看到白色,这个圆圈应该继续
最后,此动画应通知用户可以滚动视图
我怎样才能做到这一点
您可以将箭头放在UIView对象中。然后,您可以在计时器上设置UIView,在该计时器上可以正确更改alpha。不过,根据闪烁或淡入淡出,您可以使用UIView动画来完成所需的动画
override func draw(_ rect: CGRect) {
// Drawing code
self.drawArrow(from: CGPoint(x: rect.midX, y: rect.minY), to: CGPoint(x: rect.midX, y: rect.maxY),
tailWidth: 10, headWidth: 20, headLength: 15)
//arrowPath.fill()
let startColor = UIColor(red:0.87, green:0.87, blue:0.87, alpha:1.0).cgColor
let finishColor = UIColor(red:0.54, green:0.54, blue:0.57, alpha:1.0).withAlphaComponent(0.5).cgColor
let gradient = CAGradientLayer()
gradient.frame = self.bounds
gradient.colors = [startColor,finishColor]
let shapeMask = CAShapeLayer()
shapeMask.path = arrowPath.cgPath
gradient.mask = shapeMask
let animation = CABasicAnimation(keyPath: "colors")
animation.fromValue = [startColor, finishColor]
animation.toValue = [finishColor, startColor]
animation.duration = 2.0
animation.autoreverses = true
animation.repeatCount = Float.infinity
//add the animation to the gradient
gradient.add(animation, forKey: nil)
self.layer.addSublayer(gradient)
}
我说的是uiview,而不是scrollview,因为您不想隐藏scrollview。因此,您可以将它放在一个视图中,其中只有bezierpath的一个容器。您可以尝试使用CAGradientLayer和CAAnimation。为视图添加渐变:
override func viewDidAppear(animated: Bool) {
self.gradient = CAGradientLayer()
self.gradient?.frame = self.view.bounds
self.gradient?.colors = [ UIColor.white.cgColor, UIColor.white.cgColor]
self.view.layer.insertSublayer(self.gradient, atIndex: 0)
animateLayer()
}
func animateLayer(){
var fromColors = self.gradient.colors
var toColors: [AnyObject] = [UIColor.blue.cgColor,UIColor.blue.cgColor]
self.gradient.colors = toColors
var animation : CABasicAnimation = CABasicAnimation(keyPath: "colors")
animation.fromValue = fromColors
animation.toValue = toColors
animation.duration = 3.00
animation.isRemovedOnCompletion = true
animation.fillMode = CAMediaTimingFillMode.forwards
animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.linear)
animation.delegate = self
self.gradient?.addAnimation(animation, forKey:"animateGradient")
}
并按循环顺序继续渐变动画,如:
override func animationDidStop(anim: CAAnimation!, finished flag: Bool) {
self.toColors = self.fromColors;
self.fromColors = self.gradient?.colors
animateLayer()
}
我用
cabasicanition()
解决了这个问题。首先将渐变层添加到自定义UIView
,然后在其上应用遮罩,然后添加动画
override func draw(_ rect: CGRect) {
// Drawing code
self.drawArrow(from: CGPoint(x: rect.midX, y: rect.minY), to: CGPoint(x: rect.midX, y: rect.maxY),
tailWidth: 10, headWidth: 20, headLength: 15)
//arrowPath.fill()
let startColor = UIColor(red:0.87, green:0.87, blue:0.87, alpha:1.0).cgColor
let finishColor = UIColor(red:0.54, green:0.54, blue:0.57, alpha:1.0).withAlphaComponent(0.5).cgColor
let gradient = CAGradientLayer()
gradient.frame = self.bounds
gradient.colors = [startColor,finishColor]
let shapeMask = CAShapeLayer()
shapeMask.path = arrowPath.cgPath
gradient.mask = shapeMask
let animation = CABasicAnimation(keyPath: "colors")
animation.fromValue = [startColor, finishColor]
animation.toValue = [finishColor, startColor]
animation.duration = 2.0
animation.autoreverses = true
animation.repeatCount = Float.infinity
//add the animation to the gradient
gradient.add(animation, forKey: nil)
self.layer.addSublayer(gradient)
}
这将为整个自定义UIView添加渐变,而不仅仅是箭头?您需要用箭头视图替换self.view