iOS Swift 渐变扇形

iOS Swift 绘图篇 - 01 扇形渐变

效果图

override func draw(_ rect: CGRect) {
        
        
        let centerPoint = CGPoint(x: rect.width/2, y: rect.height/2)
        let radiusLength = rect.width/2
        
        
        //----------轮廓线条-----------//  不想要可以删了这段
        let color = UIColor.blue
        color.set() //设置线条颜色
        
        let endValue: Int = 30
        
        let startA = (CGFloat)((270/180)*Double.pi)
        let endA = (CGFloat)(((Double(endValue) + 270.0)/180)*Double.pi)

        let aPath = UIBezierPath()
        aPath.move(to: centerPoint)
        aPath.addArc(withCenter: centerPoint, radius: radiusLength, startAngle: endA, endAngle: startA, clockwise: false)
        aPath.stroke()
        
        //----------渐变填充-----------// 不想要可以删了这段
        
        let context = UIGraphicsGetCurrentContext()
        
        for i in 0...endValue {
            let color = UIColor(red: 1.0, green: 0, blue: 0.0, alpha: CGFloat(i)/CGFloat(endValue*2))
            context?.setFillColor(color.cgColor)
            context?.setLineWidth(0)
            context?.move(to: centerPoint)
            context?.addArc(center: centerPoint, radius: radiusLength, startAngle: CGFloat(Double(269 + i) * Double.pi / 180), endAngle: CGFloat(Double(270 + i) * Double.pi / 180), clockwise: false)
            context?.closePath()
            context?.drawPath(using: CGPathDrawingMode.fillStroke)
        }
        
    }