在Core Graphics中创build具有多个颜色段的圆

我正在试图绘制一个由相同大小的段组成的饼图，每个段都有不同的颜色。 我将我的代码放在这个SO上：在SWIFT中绘制一个圆形段的进度

let circlePath = UIBezierPath(ovalInRect: CGRect(x: 200, y: 200, width: 150, height: 150)) var segments: [CAShapeLayer] = [] let segmentAngle: CGFloat = 1.0 / CGFloat(totalSegments) for var i = 0; i < totalSegments; i++ { let circleLayer = CAShapeLayer() circleLayer.path = circlePath.CGPath // start angle is number of segments * the segment angle circleLayer.strokeStart = segmentAngle * CGFloat(i) //create a gap to show segments let gapSize: CGFloat = 0.008 circleLayer.strokeEnd = circleLayer.strokeStart + segmentAngle - gapSize circleLayer.lineWidth = 10 circleLayer.strokeColor = UIColor(red:0, green:0.004, blue:0.549, alpha:1).CGColor circleLayer.fillColor = UIColor.redColor().CGColor // add the segment to the segments array and to the view segments.insert(circleLayer, atIndex: i) view.layer.addSublayer(segments[i]) } 

但是使用这个我想要做到这一点，所以我可以根据for循环中的索引值i对每个段进行着色。 最初我只是用奇数或偶数进行testing，但发现填充部分会用最后使用的颜色填充整个圆圈。

我怀疑这是因为填充颜色填充整个圆，即使笔画有一个有限的开始和结束。 我怎样才能创build相同的效果，但为每个分段启用单独的填充颜色？

Answer 1

这里有一个饼图绘图function，我在操场上玩得很开心。 也许你可以用它来满足你的要求：

  import Foundation import UIKit // Pie Chart Drawing function // -------------------------- // - Takes an array of tuples with relative value and color for slices // - draws at center coordinates with a givn radius // func drawPieChart(slices:[(value:CGFloat, color:UIColor)], at center:CGPoint, radius:CGFloat) { // the calue component of the tuples are summed up to get the denominator for surface ratios let totalValues:CGFloat = slices.reduce(0, combine: {$0 + $1.value}) // starting at noon (-90deg) var angle:CGFloat = -CGFloat(M_PI)/2 // draw each slice going counter clockwise for (value,color) in slices { let path = UIBezierPath() // slice's angle is proportional to circumference 2π let sliceAngle = CGFloat(M_PI)*2*value/totalValues // select fill color from tuple color.setFill() // draw pie slice using arc from center and closing path back to center path.moveToPoint(center) path.addArcWithCenter( center, radius: radius, startAngle: angle, endAngle: angle - sliceAngle, clockwise: false ) path.moveToPoint(center) path.closePath() // draw slice in current context path.fill() // offset angle for next slice angle -= sliceAngle } } // Pie chart Data let slices:[(value:CGFloat, color:UIColor)] = [ (3, UIColor.greenColor()), (5, UIColor.redColor()), (8, UIColor.blueColor()), (13,UIColor.yellowColor()) ] // UIView let viewSize = CGSize(width: 300, height: 300) let view:UIView = UIView(frame: CGRect(origin: CGPointZero, size: viewSize)) view.backgroundColor = UIColor.whiteColor() // CoreGraphics drawing UIGraphicsBeginImageContextWithOptions(viewSize, false, 0) // draw pie chart in Image context drawPieChart(slices, at:CGPointMake(150,150), radius:100 ) // set image to view layer (you could also use it elsewhere) view.layer.contents = UIGraphicsGetImageFromCurrentImageContext().CGImage UIGraphicsEndImageContext() // Playground (quick look or Timeline) let preview = view 

注意：要获得相同大小的段，只需在元组数组的所有条目中提供相同的值。