Question

我希望在屏幕中央有一条线，并像蛇一样动画它

这是我想制作的一步一步的动画

我该怎么做？

Answer 1

您可以在path上为CAShapeLayer的笔画末尾设置动画，例如，

weak var shapeLayer: CAShapeLayer?

@IBAction func didTapButton(_ sender: Any) {
    // remove old shape layer if any

    self.shapeLayer?.removeFromSuperlayer()

    // create whatever path you want

    let path = UIBezierPath()
    path.move(to: CGPoint(x: 10, y: 50))
    path.addLine(to: CGPoint(x: 200, y: 50))
    path.addLine(to: CGPoint(x: 200, y: 240))

    // create shape layer for that path

    let shapeLayer = CAShapeLayer()
    shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
    shapeLayer.strokeColor = #colorLiteral(red: 1, green: 0, blue: 0, alpha: 1).cgColor
    shapeLayer.lineWidth = 4
    shapeLayer.path = path.cgPath

    // animate it

    view.layer.addSublayer(shapeLayer)
    let animation = CABasicAnimation(keyPath: "strokeEnd")
    animation.fromValue = 0
    animation.duration = 2
    shapeLayer.add(animation, forKey: "MyAnimation")

    // save shape layer

    self.shapeLayer = shapeLayer
}

产量：

显然，您可以将UIBezierPath更改为符合您兴趣的内容。例如，您可以在路径中包含空格。或者你甚至不需要有直线路径：

let path = UIBezierPath()
path.move(to: CGPoint(x: 10, y: 130))
path.addCurve(to: CGPoint(x: 210, y: 200), controlPoint1: CGPoint(x: 50, y: -100), controlPoint2: CGPoint(x: 100, y: 350))

您还可以在CAAnimationGroup：

中组合笔画开始和结束的动画

// create shape layer for that path (this defines what the path looks like when the animation is done)

let shapeLayer = CAShapeLayer()
shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
shapeLayer.strokeColor = #colorLiteral(red: 1, green: 0, blue: 0, alpha: 1).cgColor
shapeLayer.lineWidth = 5
shapeLayer.path = path.cgPath
shapeLayer.strokeStart = 0.8

let startAnimation = CABasicAnimation(keyPath: "strokeStart")
startAnimation.fromValue = 0
startAnimation.toValue = 0.8

let endAnimation = CABasicAnimation(keyPath: "strokeEnd")
endAnimation.fromValue = 0.2
endAnimation.toValue = 1.0

let animation = CAAnimationGroup()
animation.animations = [startAnimation, endAnimation]
animation.duration = 2
shapeLayer.add(animation, forKey: "MyAnimation")

产量：

CoreAnimation让您可以很好地控制描边路径的呈现方式。

Answer 2

我的需求类似 - 想让场景的动作在场景中追踪一条线，但是很难将CAShapeLayer中的动画与SKScene中的动画同步。

所以最终采用了不同的方法：

import SpriteKit
import PlaygroundSupport
import AVFoundation

let start = CGPoint(x: 100, y: 50)
let end = CGPoint(x: 200, y: 50)
let control = CGPoint(x: 150, y: 100);
var motion: SKAction = SKAction();

let radius: CGFloat = 20;
let bounds = CGRect(x: 0, y: 0, width: 400, height: 200)
let skview = SKView(frame: bounds)
PlaygroundPage.current.liveView = skview
PlaygroundPage.current.needsIndefiniteExecution = true

class MyScene: SKScene,AVSpeechSynthesizerDelegate {
    var motionComplete = false
    var redline: SKShapeNode = SKShapeNode();
    var greenball: SKShapeNode = SKShapeNode();
    override func sceneDidLoad() {

        greenball = SKShapeNode(circleOfRadius: radius);
        greenball.position = start;
        greenball.fillColor = .green;

        let motionpath = CGMutablePath();

        motionpath.move(to: start)
        motionpath.addQuadCurve(to: end, control: control)

        motion = SKAction.follow(motionpath, asOffset: false, orientToPath: true,duration: 2);

        let linepath = CGMutablePath();
        linepath.move(to: start);
        redline = SKShapeNode(path: linepath);
        redline.strokeColor = .red;
        redline.lineWidth = 5;

        greenball.run(motion) {
            self.motionComplete = true;
        };

        self.addChild(greenball);
        self.addChild(redline);
    }

    override func update(_ currentTime: TimeInterval) {

        if (motionComplete == false) {
            let cgpath = self.redline.path as! CGMutablePath;
            cgpath.addLine(to: greenball.position);
            self.redline.path = cgpath;

        }
    }


}



let scene = MyScene(size: CGSize(width: 400, height: 200));
scene.scaleMode = SKSceneScaleMode.aspectFill
scene.size = skview.bounds.size
skview.presentScene(scene)

结果：

Answer 3

一种方法是使用具有背景颜色的UIView。尝试这样的事情。

df['value_day_normalized'] = df['value'].div(df.resample('D')['value'].transform('sum'))
print (df)
                              value  value_day_normalized
datetime                                                 
2017-03-08 14:36:06.616166  1002.49              0.053239
2017-03-08 15:06:07.661818   992.68              0.052718
2017-03-08 15:36:08.597443   984.34              0.052275
2017-03-08 16:06:09.265451   989.32              0.052539
2017-03-08 16:36:10.581452  1004.00              0.053319
2017-03-08 17:06:11.269434  1003.97              0.053317
2017-03-08 17:36:12.117443   994.80              0.052830
...
...

有了这个，你可以实现任何数量的红线移动。

另一种方法是实际绘制一条线。我不会详细了解这一点，但会推荐。

最后一件事......在堆栈溢出时，我们感谢那些在询问问题之前表明他们正确研究过主题的人。使用谷歌，我能够快速提出许多关于如何做你正在寻找的教程。尝试自己做研究，因为通常教程会有比堆栈溢出答案更重要的细节。

Answer 4

此技术也可以使用，它作为边框添加，您可以按自己的方式进行模制。首先创建路径，然后在其上画线

    let path = UIBezierPath()

我已经根据需要指定了x，y值，您可以根据自己的需要进行更改

path.move(to: CGPoint(x: 134, y: 209))//
    path.addLine(to: CGPoint(x: (131 + 93), y: 209))// for drawing line
    path.addQuadCurve(to: CGPoint(x: (131 + 97), y: 212) , controlPoint: CGPoint(x: (131 + 93), y: 209))// for drawing a curve
    path.addLine(to: CGPoint(x: (131 + 97) , y: (209 + 33 )))
    path.addQuadCurve(to: CGPoint(x: (131 + 93), y: (209 + 37)), controlPoint:  CGPoint(x: (131 + 97) , y: (209 + 33 )))
    path.addLine(to: CGPoint(x: 135, y: (209 + 37)))
    path.addQuadCurve(to: CGPoint(x: 131, y: 209 + 33), controlPoint: CGPoint(x: 135, y: 209 + 37))
    path.addLine(to: CGPoint(x: 131, y: 213))
    path.addQuadCurve(to: CGPoint(x: 134, y: 209), controlPoint:CGPoint(x: 131, y: 213) )
     let shapelayer = CAShapeLayer()//create shape layer object
    shapelayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
    shapelayer.strokeColor = #colorLiteral(red: 0.06274510175, green: 0, blue: 0.1921568662, alpha: 1).cgColor
    shapelayer.lineWidth = 2
    shapelayer.path = path.cgPath
    view.layer.addSublayer(shapelayer)
    let animation = CABasicAnimation(keyPath: "strokeEnd")// create animation and add it to shape layer
    animation.fromValue = 0
    animation.duration = 3
    shapelayer.add(animation, forKey: "MyAnimation")
    self.shapelayer = shapelayer

仅此而已。希望它能对某人有所帮助，因为我也花了几个小时才做到了，因为没有找到确切的解决方案。还要检查此链接：

https://github.com/Shahijabeen/BorderAnimation

画线动画

4 个答案: