Swift UIView Peaked View

SwiftPeakView.swift

//
//  SwiftPeakView.swift
//
//  Created by Thorn, David on 30.03.20.
//  Copyright © 2020 Thorn, David. All rights reserved.
//
  
import UIKit

protocol CreatePeak {
    func drawPeak(rect: CGRect,
                  peakWidth: CGFloat,
                  cornerRadius: CGFloat,
                  strokeWidth: CGFloat,
                  strokeColor: UIColor,
                  context: CGContext)
}

extension CreatePeak {
    
    func drawPeak(rect: CGRect,
                  peakWidth: CGFloat,
                  cornerRadius: CGFloat = 20,
                  strokeWidth: CGFloat = 2,
                  strokeColor: UIColor,
                  context: CGContext) {

        let xLength = rect.size.width - strokeWidth
        let yLength = rect.size.height - peakWidth - (cornerRadius * 2) - strokeWidth
        let halfWayWidth = (xLength / 2) - cornerRadius

        let start = CGPoint(x: rect.origin.x + (strokeWidth / 2),
                            y: rect.origin.y + cornerRadius + (strokeWidth / 2))

        context.move(to: start) // start should be top left corner

        let bottomLeftCornerPre = CGPoint(x: start.x, y: start.y + yLength)
        context.addLine(to: bottomLeftCornerPre)
        context.setLineWidth(strokeWidth)

        let control1 = CGPoint(x: start.x, y: bottomLeftCornerPre.y + cornerRadius)
        let bottomLeftCornerPost = CGPoint(x: bottomLeftCornerPre.x + cornerRadius, y: bottomLeftCornerPre.y + cornerRadius)
        context.addQuadCurve(to: bottomLeftCornerPost, control: control1)

        let leftPeakEdge = CGPoint(x: bottomLeftCornerPost.x + (halfWayWidth - peakWidth),
                                   y: bottomLeftCornerPost.y)
        context.addLine(to: leftPeakEdge)

        let bottomPeakEdge = CGPoint(x: leftPeakEdge.x + peakWidth,
                                     y: leftPeakEdge.y + peakWidth)
        context.addLine(to: bottomPeakEdge)

        let rightPeakEdge = CGPoint(x: bottomPeakEdge.x + peakWidth,
                                    y: bottomPeakEdge.y - peakWidth)
        context.addLine(to: rightPeakEdge)

        let bottomRightCorner = CGPoint(x: rightPeakEdge.x + halfWayWidth - peakWidth,
                                        y: rightPeakEdge.y)
        context.addLine(to: bottomRightCorner)

        let control2 = CGPoint(x: bottomRightCorner.x + cornerRadius,
                               y: bottomRightCorner.y)
        let bottomRightCornerPost = CGPoint(x: bottomRightCorner.x + cornerRadius, y: bottomRightCorner.y - cornerRadius)
        context.addQuadCurve(to: bottomRightCornerPost, control: control2)

        let topRightCorner = CGPoint(x: bottomRightCornerPost.x,
                                     y: start.y)
        context.addLine(to: topRightCorner)

        let control3 = CGPoint(x: topRightCorner.x, y: topRightCorner.y - cornerRadius)
        let topRightCornerPre = CGPoint(x: topRightCorner.x - cornerRadius,
                                        y: topRightCorner.y - cornerRadius)
        context.addQuadCurve(to: topRightCornerPre, control: control3)

        let topLeftCorner = CGPoint(x: start.x + cornerRadius,
                                    y: start.y - cornerRadius)
        context.addLine(to: topLeftCorner)

        let control4 = CGPoint(x: topLeftCorner.x - cornerRadius,
                               y: topLeftCorner.y)
        let topLeftCornerPost = CGPoint(x: start.x, y: start.y)
        context.addQuadCurve(to: topLeftCornerPost, control: control4)

        context.setStrokeColor(strokeColor.cgColor)
        context.strokePath()
    }
}