[SWIFT] Draw a gradient with CAGradientLayer

I had the opportunity to draw a gradient in UIView using CAGradientLayer I briefly summarized the mounting method.

Prerequisite knowledge

startPoint ・ ・ ・ Start point of gradation endPoint ・ ・ ・ End point of gradation

When startPoint and endPoint are not specified

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        setGradation()
    }

    private func setGradation() {
        let gradientLayer = CAGradientLayer()
　　　　 //Specify the range to be gradation to the view size of UIViewController
        gradientLayer.frame.size = self.view.frame.size
        gradientLayer.colors = [UIColor.green.cgColor, UIColor.white.cgColor]
        self.view.layer.addSublayer(gradientLayer)
    }
}

The default values ​​of startPoint and endPoint of the gradation are as follows (gradient from top center to bottom center)

It is drawn as follows.

When specifying startPoint and endPoint

As mentioned above, the values ​​of startPoint and endPoint of the gradation are set by default, but you can also specify them. In the code below startPoint: CGPoint (x: 0.0, y: 1.0) (lower left) endPoint: CGPoint (x: 1.0, y: 0.0) (upper right) Therefore, it will be drawn as shown in the capture below.

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        
        setGradation()
    }

    private func setGradation() {
        let gradientLayer = CAGradientLayer()
　　　　　//Specify the range to be gradation to the view size of UIViewController
        gradientLayer.frame.size = self.view.frame.size
        gradientLayer.colors = [UIColor.blue.cgColor, UIColor.white.cgColor]
        gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
        gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.0)
        self.view.layer.addSublayer(gradientLayer)
    }
}