TransparentTriangleSwift4.swift

// 
// Transparent Triangle in Swift 4.2
// (c) 2019 by Jeff Algera
// MIT License
//
class TransparentTriangleView: UIView {
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        isOpaque = false
        backgroundColor = UIColor.clear
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override func draw(_ rect: CGRect) {
        guard let context = UIGraphicsGetCurrentContext() else { return }
        context.clear(rect)
        context.beginPath()
        context.move(to: CGPoint(x: rect.maxX, y: rect.minY))
        context.addLine(to: CGPoint(x: rect.minX, y: rect.maxY))
        context.addLine(to: CGPoint(x: rect.minX, y: rect.minY))
        context.closePath()
        
        context.setFillColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.0667)
        context.fillPath()
    }
}