triangleview.swift

class TriangleView: UIView {

    override func draw(_ rect: CGRect) {
        guard let context = UIGraphicsGetCurrentContext() else { return }
        context.beginPath()
        context.move(to: CGPoint(x: rect.midX, y: rect.minY))
        context.addLine(to: CGPoint(x: rect.minX, y: rect.maxY))
        context.addLine(to: CGPoint(x: rect.maxX, y: rect.maxY))
        context.closePath()
        context.setFillColor(UIColor.black.withAlphaComponent(0.6).cgColor)
        context.fillPath()
    }
}