v-h-alpha-view.swift

//: Playground - noun: a place where people can play
// Vertical and Horizontal alpha view demo
// Xcode9 required

import UIKit
do {
    let v = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 500))
    v.backgroundColor = .clear
    let horizontalGradientLayer = CAGradientLayer()
    horizontalGradientLayer.frame = v.frame
    horizontalGradientLayer.startPoint = CGPoint(x: 0, y: 0.5)
    horizontalGradientLayer.endPoint = CGPoint(x: 65 / 500, y: 0.5)
    horizontalGradientLayer.colors = [(0.84, 0.0), (0.93, 1.0)].map { UIColor(red: $0, green: $0, blue: $0, alpha: $1).cgColor }
    v.layer.mask = horizontalGradientLayer
    let v2 = UIView(frame: v.frame)
    v2.backgroundColor = .green
    let verticalGradientLayer = CAGradientLayer()
    verticalGradientLayer.frame = v.frame
    verticalGradientLayer.startPoint = CGPoint(x: 0.5, y: 0)
    verticalGradientLayer.endPoint = CGPoint(x: 0.5, y: 65 / 500)
    verticalGradientLayer.colors = [(0.84, 0.0), (0.93, 1.0)].map { UIColor(red: $0, green: $0, blue: $0, alpha: $1).cgColor }
    v2.layer.mask = verticalGradientLayer
    v.addSubview(v2)
    let button = UIButton(frame: CGRect(x: 0, y: 0, width: 100, height: 40))
    button.backgroundColor = .red
    button.setTitle("hello", for: .normal)
    button.titleLabel?.font = UIFont.systemFont(ofSize: 40)
    button.setTitleColor(.black, for: .normal)
    v2.addSubview(button)
    v
}

do {
    let v = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 500))
    v.backgroundColor = .orange
    let horizontalGradientLayer = CAGradientLayer()
    horizontalGradientLayer.frame = v.frame
    horizontalGradientLayer.startPoint = CGPoint(x: 0, y: 0.5)
    horizontalGradientLayer.endPoint = CGPoint(x: 65 / 500, y: 0.5)
    horizontalGradientLayer.colors = [(0.84, 0.0), (0.93, 1.0)].map { UIColor(red: $0, green: $0, blue: $0, alpha: $1).cgColor }
    let verticalGradientLayer = CAGradientLayer()
    verticalGradientLayer.frame = v.frame
    verticalGradientLayer.startPoint = CGPoint(x: 0.5, y: 0)
    verticalGradientLayer.endPoint = CGPoint(x: 0.5, y: 65 / 500)
    verticalGradientLayer.colors = [(0.84, 0.0), (0.93, 1.0)].map { UIColor(red: $0, green: $0, blue: $0, alpha: $1).cgColor }
    let button = UIButton(frame: CGRect(x: 20, y: 0, width: 100, height: 40))
    button.setTitle("hello", for: .normal)
    button.titleLabel?.font = UIFont.systemFont(ofSize: 40)
    button.setTitleColor(.black, for: .normal)
    v.addSubview(button)
    v.layer.mask = horizontalGradientLayer
    horizontalGradientLayer.addSublayer(verticalGradientLayer)
    v
}