CoreGraphics draw a line with gradient and lineCap

GradientLine.swift

class GradientLineView: UIView {
    
    override func draw(_ rect: CGRect) {
        if let context = UIGraphicsGetCurrentContext() {
            let startPoint1 = CGPoint(x: 20, y: rect.height/2)
            let endPoint1 = CGPoint(x: rect.width-120, y: rect.height/2)
            context.setLineWidth(15)
            context.move(to: startPoint1)
            context.addLine(to: endPoint1)
            context.setLineCap(.round)
            context.setStrokeColor(UIColor.red.cgColor)
            context.replacePathWithStrokedPath()
            context.clip()
            let startPoint2 = CGPoint(x: 0, y: rect.height/2)
            let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: [UIColor.blue.cgColor, UIColor.green.cgColor] as CFArray, locations: [0.3, 0.7])
            context.drawLinearGradient(gradient!, start: startPoint2, end: endPoint1, options: CGGradientDrawingOptions.drawsAfterEndLocation)
            
        }
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        backgroundColor = UIColor.clear
    }
    
}

// Test in Playgoround

let v = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 500))
v.backgroundColor = UIColor.white

let p = GradientLineView(frame: CGRect(x: 20, y: 20, width: 200, height: 50))
v.addSubview(p)
PlaygroundPage.current.liveView = v
PlaygroundPage.current.needsIndefiniteExecution = true