如何快速根据圆圈中的百分比填充笔触颜色

问题描述

我正在创建一个圆圈并分成四个部分。笔触颜色应根据给定的百分比填充。

    func showCircle() {
    dispatchQueue.main.asyncAfter(deadline: dispatchTime.Now()+0.2) { [weak self] in
        guard let `self` = self else { return }
         
        self.layer.cornerRadius = self.frame.size.width / 2
        self.backgroundColor = .clear
           let total: Int = 4
           let width: CGFloat = 10.0
           let reducer: CGFloat = 0.0 // add gape b/w segments if reducer > 0
           let circlePath = UIBezierPath(arcCenter: CGPoint(x: self.frame.size.width / 2,y: self.frame.size.height / 2),radius: self.frame.size.width / 2,startAngle: CGFloat(-0.5 * Double.pi),endAngle: CGFloat(1.5 * Double.pi),clockwise: true)
      
        // these are the percentages 
        let percentages = [0.20,0.15,0.35,0.30]
           
           for i in 1...total {
            
            let percentage = CGFloat(percentages[i - 1] )

            let circleShape = CAShapeLayer()
               circleShape.path = circlePath.cgPath
            
            switch i-1 {
            case 0:
                circleShape.strokeColor = #colorLiteral(red: 0.431372549,green: 0.231372549,blue: 0.631372549,alpha: 1)
                
            case 1:
                circleShape.strokeColor = #colorLiteral(red: 0.6784313725,green: 0.568627451,blue: 0.7882352941,alpha: 1)
                
            case 2:
                circleShape.strokeColor = #colorLiteral(red: 0.8470588235,green: 0.7960784314,blue: 0.8980392157,alpha: 1)
                
            case 3:
                circleShape.strokeColor = #colorLiteral(red: 0.9490196078,green: 0.937254902,blue: 0.9568627451,alpha: 1)
            default:
                circleShape.strokeColor = #colorLiteral(red: 0,green: 0,blue: 0,alpha: 1)
            }
               circleShape.fillColor = UIColor.clear.cgColor
               circleShape.linewidth = width
               circleShape.strokeStart = CGFloat(CGFloat(i - 1) * percentage) + reducer
               circleShape.strokeEnd = CGFloat(CGFloat(i) * percentage) - reducer
            self.layer.addSublayer(circleShape)
           }
        }
}

错误的结果：- 这些颜色应根据百分比填充。

预期结果：- 我们可以在这张图片中看到颜色根据百分比正确填充。

解决方法

你的错误是strokeStart和strokeEnd应该从0到1并且随着索引的增加而增加。

这是行得通的：

    // these are the percentages
    let percentages = [0.20,0.15,0.35,0.30]
    
    for i in 1...total {
        let prevPercentage: Double = percentages.prefix(i - 1).reduce(0,+)
        let percentage = percentages[i - 1]
        
        let circleShape = CAShapeLayer()
        circleShape.path = circlePath.cgPath
        
        switch i-1 {
        case 0:
            circleShape.strokeColor = UIColor.red.cgColor
            
        case 1:
            circleShape.strokeColor = UIColor.green.cgColor
            
        case 2:
            circleShape.strokeColor = UIColor.blue.cgColor
            
        case 3:
            circleShape.strokeColor = UIColor.orange.cgColor
        default:
            circleShape.strokeColor = #colorLiteral(red: 0,green: 0,blue: 0,alpha: 1)
        }
        circleShape.fillColor = UIColor.clear.cgColor
        circleShape.lineWidth = width
        circleShape.strokeStart = CGFloat(prevPercentage)
        circleShape.strokeEnd = CGFloat(prevPercentage + percentage)
        view.layer.addSublayer(circleShape)
    }

结果：