Ios CAShapeLayer遮罩从底部露出

我试图从图像的底部创建一个“显示”效果。 我原以为它会像将anchorPoint设置为CGPointMake（0.5，1.0）或将contentsGravity设置为kCAGravityTop一样简单，但这些选项都不起作用

我的当前代码可以工作，但可以从上到下设置动画。以下是展示的想法：

我该如何让它从下到上

这是密码

    let path                = UIBezierPath(rect: CGRectMake(0, 0, imgEmptyBase.width, imgEmptyBase.height - 80))
    let mask                = CAShapeLayer()
    mask.anchorPoint        = CGPointMake(0.5, 1.0)
    mask.path               = path.CGPath

    imgEmptyBase.layer.mask = mask

    let anim                = CABasicAnimation(keyPath: "path")

    anim.fromValue          = path.CGPath
    anim.toValue            = UIBezierPath(rect: imgEmptyBase.bounds).CGPath
    anim.duration           = 1.0
    anim.fillMode           = kCAFillModeForwards
    anim.removedOnCompletion = false

    imgEmptyBase.layer.mask.addAnimation(anim, forKey: "anim")

我想到了（2）个选项

一种是仅将动画从和切换到值：

let path                = UIBezierPath(rect: CGRectMake(0, 0, imgEmptyBase.width, imgEmptyBase.height - 80))
let mask                = CAShapeLayer()
mask.anchorPoint        = CGPointMake(0.5, 1.0)
mask.path               = path.CGPath

imgEmptyBase.layer.mask = mask

let anim                = CABasicAnimation(keyPath: "path")

anim.fromValue          = UIBezierPath(rect: imgEmptyBase.bounds).CGPath
anim.toValue            = path.CGPath
anim.duration           = 1.0
anim.fillMode           = kCAFillModeForwards
anim.removedOnCompletion = false

imgEmptyBase.layer.mask.addAnimation(anim, forKey: "anim")

另一个是切换bezier路径声明本身：

let path                = UIBezierPath(rect: imgEmptyBase.bounds).CGPath
let mask                = CAShapeLayer()
mask.anchorPoint        = CGPointMake(0.5, 1.0)
mask.path               = path.CGPath

imgEmptyBase.layer.mask = mask

let anim                = CABasicAnimation(keyPath: "path")

anim.fromValue          = path.CGPath
anim.toValue            = UIBezierPath(rect: CGRectMake(0, 0, imgEmptyBase.width, imgEmptyBase.height - 80))
anim.duration           = 1.0
anim.fillMode           = kCAFillModeForwards
anim.removedOnCompletion = false

imgEmptyBase.layer.mask.addAnimation(anim, forKey: "anim")

检查这个

let path = UIBezierPath(rect: CGRectMake(0, denterImage.frame.origin.y, denterImage.bounds.size.width, denterImage.bounds.size.height - 200))
let mask = CAShapeLayer()
mask.anchorPoint = CGPointMake(0.5, 1.0)
mask.path = path.CGPath

denterImage.layer.mask = mask

let anim = CABasicAnimation(keyPath: "path")

anim.fromValue = path.CGPath
anim.toValue = UIBezierPath(rect: denterImage.bounds).CGPath
anim.duration =  1.5
anim.fillMode = kCAFillModeForwards
anim.removedOnCompletion = false

denterImage.layer.mask.addAnimation(anim, forKey: "anim")

---

我的建议是使用路径的笔划而不是填充

绘制一条路径（蓝线），从图层底部开始，到图层顶部结束，水平居中，线宽与图层宽度相同。
红色轮廓表示笔划轮廓

您可以在

strokeEnd

属性上从0到1播放动画

如果你想看看我是怎么做到的

我更新了上面的链接。
我写了密码，以防你还不能去操场

let aView = UIView(frame:CGRect(x:0 y:0 width:200 height:200))
aView.backgroundColor = UIColor.redColor() // the view that needs to be masked
let shapeLayer = CAShapeLayer()
shapeLayer.bounds = aView.bounds
let bezierPath = UIBezierPath()
bezierPath.moveToPoint(CGPoint(x: shapeLayer.bounds.width/2, y: shapeLayer.bounds.height))
bezierPath.addLineToPoint(CGPoint(x: shapeLayer.bounds.width/2, y: 0))
shapeLayer.path = bezierPath.CGPath
shapeLayer.fillColor = UIColor.clearColor().CGColor
shapeLayer.strokeColor = UIColor.redColor().CGColor
shapeLayer.lineWidth = shapeLayer.bounds.width
shapeLayer.position = CGPoint(x: aView.frame.width/2, y: aView.frame.height/2)
shapeLayer.strokeEnd = 1

let animation = CABasicAnimation(keyPath: "strokeEnd")
animation.fromValue = 0
animation.toValue = 1
animation.duration = 4
animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
shapeLayer.addAnimation(animation, forKey: "stroneAnimation")
shapeLayer.strokeEnd = 1
aView.layer.mask = shapeLayer

---

这将完全达到您想要的效果：

let path = UIBezierPath(rect: CGRectMake(0, imgEmptyBase.layer.frame.size.height, imgEmptyBase.layer.frame.size.width, imgEmptyBase.layer.frame.size.height))
let mask = CAShapeLayer()
mask.path = path.CGPath

imgEmptyBase.layer.mask = mask

let revealPath = UIBezierPath(rect: CGRectMake(0, 0, imgEmptyBase.layer.frame.size.width, imgEmptyBase.layer.frame.size.height))

let anim                = CABasicAnimation(keyPath: "path")
anim.fromValue          = path.CGPath
anim.toValue            = revealPath.CGPath
anim.duration           = 1.0
anim.fillMode           = kCAFillModeForwards
anim.removedOnCompletion = false

imgEmptyBase.layer.mask.addAnimation(anim, forKey: "anim")

---

所有这些都是关于使用正确的“from”和“to”值更改遮罩路径。例如：将初始遮罩路径设置为

CGRectMake（0,0，imgEmptyBase.layer.frame.size.width，0）

和

revealPath

设置为

CGRectMake（0,0，imgEmptyBase.layer.frame.size.width，imgEmptyBase.layer.frame.size.height）

将产生“从上到下”的显示效果。

这两个选项都会隐藏该项。。。我想透露一下。翻转值并不能解决问题…你的游乐场链接不起作用。你能提供一些代码吗？我用一个新的链接更新了帖子，并粘贴了代码