addArc（withCenter）关闭路径

Question

下面的代码：

let size = CGSize(width: 200, height: 30) 
    let rect = CGRect(origin: .zero, size: size) 

    let path1 = UIBezierPath() 
    path1.move(to: CGPoint(x: 10, y: 5)) 
    path1.addLine(to: CGPoint(x: 180, y: 5)) 
    path1.addArc(withCenter: CGPoint(x: 180, y: 20), radius: 15, 
    startAngle: (3.14159/2), endAngle: (3 * 3.14159/2), clockwise: false) 

产生这样的：

好吧，我失去的东西吗？我不想关闭这条路。我从来不打电话给path1.close()。我想从弧的末端添加另一条直线，而不是从封闭的版本开始。基本上，我不希望半圈被关闭，我该怎么做？

Answer 1

你需要在-90度开始你的弧度并以+90度结束。你也需要改变方向。你需要做如下：

path1.addArc(withCenter: CGPoint(x: 180, y: 20), radius: 15, startAngle: -.pi/2, endAngle: .pi/2, clockwise: true) 

如果你想完成的形状也应该是这样的：

let path1 = UIBezierPath() 
path1.move(to: CGPoint(x: 10, y: 5)) 
path1.addLine(to: CGPoint(x: 180, y: 5)) 
path1.addArc(withCenter: CGPoint(x: 180, y: 20), radius: 15, startAngle: -.pi/2, endAngle: .pi/2, clockwise: true) 
path1.addLine(to: CGPoint(x: 10, y: 35)) 
path1.addArc(withCenter: CGPoint(x: 10, y: 20), radius: 15, startAngle: .pi/2, endAngle:-.pi/2 , clockwise: true) 

Answer 2

希望这将帮助你实现你的结果

let size = CGRect(origin: .zero, size: CGSize(width : 200 , height : 30)) 

     let path = UIBezierPath() 
     path.move(to: CGPoint(x: 10, y: 100)) 
     path.addLine(to: CGPoint(x: 180, y: 100)) 
     path.addArc(withCenter: CGPoint(x:180 , y: 85), radius: 15, startAngle: (3.14159/2), endAngle: (3 * 3.14159/2), clockwise: false) 

    path.addLine(to: CGPoint(x: 10, y: 70)) //y = radius * 2 

上面的代码将在您的画布中绘制此图。