用UIBezierPath在Swift中创造曙光

import UIKit

class SunriseView: UIView {
    
    override func draw(_ rect: CGRect) {
        // 创建曙光的起点和终点
        let startPoint = CGPoint(x: rect.midX, y: rect.minY)
        let endPoint = CGPoint(x: rect.midX, y: rect.maxY)
        
        // 创建曙光的颜色渐变
        let colors = [UIColor.yellow.cgColor, UIColor.clear.cgColor]
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let colorLocations: [CGFloat] = [0.0, 1.0]
        let gradient = CGGradient(colorsSpace: colorSpace, colors: colors as CFArray, locations: colorLocations)!
        
        // 创建UIBezierPath对象
        let path = UIBezierPath()
        
        // 设置曙光的起点和终点
        path.move(to: startPoint)
        path.addLine(to: endPoint)
        
        // 将UIBezierPath对象添加到当前上下文中
        let context = UIGraphicsGetCurrentContext()!
        context.addPath(path.cgPath)
        
        // 设置渐变填充
        context.clip()
        context.drawLinearGradient(gradient, start: startPoint, end: endPoint, options: [])
    }
}

import UIKit

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建曙光视图
        let sunriseView = SunriseView(frame: CGRect(x: 50, y: 50, width: 200, height: 200))
        sunriseView.backgroundColor = UIColor.black
        
        // 将曙光视图添加到当前视图中
        view.addSubview(sunriseView)
    }
}