在使用-draw绘制字符串时对字符串应用渐变颜色(在:withAttributes:中)

// 导入Core Graphics框架
import CoreGraphics

// 要绘制的字符串
let text = "Hello, World!"

// 创建NSMutableAttributedString对象
let attributedText = NSMutableAttributedString(string: text)

// 添加渐变颜色属性
let gradientColors = [UIColor.red.cgColor, UIColor.blue.cgColor] // 渐变颜色数组
let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: gradientColors as CFArray, locations: nil)
attributedText.addAttribute(.foregroundColor, value: gradient, range: NSRange(location: 0, length: attributedText.length))

// 创建CGContextRef对象
let context = UIGraphicsGetCurrentContext()

// 设置渐变颜色的起始点和结束点
let startPoint = CGPoint(x: 0, y: 0)
let endPoint = CGPoint(x: 0, y: 100)

// 绘制字符串
attributedText.draw(with: CGRect(x: 0, y: 0, width: 100, height: 100), options: .usesLineFragmentOrigin, context: context)