Question

I drew a circle but when I try to add another circle a line connects both circles.

import UIKit

class skills: UIView {

    override func drawRect(rect: CGRect)
    {
        var startAngle: Float = Float(2 * M_PI)
        var endAngle: Float = 0.0
        var endAngletwo: Float = 2.0

        // Drawing code
        // Set the radius
        let strokeWidth = 10.0
        let radius = CGFloat((CGFloat(self.frame.size.width) - CGFloat(strokeWidth)) / 20)


        // Get the context
        var context = UIGraphicsGetCurrentContext()



        **// Find the middle of the circle
        let center = CGPointMake(100, 200)

        let inside = CGPointMake(100,400)**

        // Set the stroke color
        CGContextSetStrokeColorWithColor(context, UIColor.whiteColor().CGColor)

        // Set the line width
        CGContextSetLineWidth(context, CGFloat(strokeWidth))

        // Set the fill color (if you are filling the circle)
        CGContextSetFillColorWithColor(context, UIColor.clearColor().CGColor)

        // Rotate the angles so that the inputted angles are intuitive like the clock face: the top is 0 (or 2π), the right is π/2, the bottom is π and the left is 3π/2.
        // In essence, this appears like a unit circle rotated π/2 anti clockwise.
        startAngle = startAngle - Float(M_PI_2)
        endAngle = endAngle - Float(M_PI_2)
        endAngletwo = endAngletwo - Float(M_2_PI)

        // Draw the arc around the circle
        CGContextAddArc(context, center.x, center.y, CGFloat(radius), CGFloat(startAngle), CGFloat(endAngle), 0)

        CGContextAddArc(context, inside.x, inside.y, CGFloat(radius), CGFloat(startAngle), CGFloat(endAngletwo),0)

        // Draw the arc
        CGContextDrawPath(context, kCGPathStroke) // or kCGPathFillStroke to fill and stroke the circle







    }










}

I think the problem is where the //Find the middle of the circle is because when Swift detects CGPointMake it will connect the two points? I think, i'm not too sure. How would I fix this?

Answer 1

来自tofile文档：

如果当前路径已包含子路径，Quartz会添加一行将当前点连接到弧的起始点。如果当前路径为空，Quartz创建一个带有的新子路径起点设置为弧的起点。

因此你必须＆＃34;搬到＆＃34;首先是圈子的起点：

CGContextAddArc()

（如果您使用CGContextMoveToPoint(context, center.x + CGFloat(cos(startAngle)) * radius, center.y + CGFloat(sin(startAngle)) * radius) CGContextAddArc(context, center.x, center.y, CGFloat(radius), CGFloat(startAngle), CGFloat(endAngle), 0) CGContextMoveToPoint(context, inside.x + CGFloat(cos(startAngle)) * radius, inside.y + CGFloat(sin(startAngle)) * radius) CGContextAddArc(context, inside.x, inside.y, CGFloat(radius), CGFloat(startAngle), CGFloat(endAngletwo),0)而不是CGFloat / CGFloat`混合使用，则需要更少的类型对话。）

或者使用Float绘制一个完整的圆圈。

Trying to draw multiple circles but both circles connect with a line

1 个答案: