CGGradient现在可以在UIBazierPath上绘制精确的颜色

// 创建渐变颜色空间
let colorSpace = CGColorSpaceCreateDeviceRGB()

// 定义渐变颜色
let colors = [
    UIColor.red.cgColor,
    UIColor.blue.cgColor
]

// 定义颜色位置
let locations: [CGFloat] = [0.0, 1.0]

// 创建渐变对象
let gradient = CGGradient(colorsSpace: colorSpace, colors: colors as CFArray, locations: locations)

// 获取绘制上下文
let context = UIGraphicsGetCurrentContext()

// 创建路径
let path = UIBezierPath(rect: CGRect(x: 0, y: 0, width: 100, height: 100))

// 将路径添加到上下文中
context?.addPath(path.cgPath)

// 使用渐变填充路径
context?.saveGState()
context?.clip()
context?.drawLinearGradient(gradient!, start: CGPoint(x: 0, y: 0), end: CGPoint(x: 100, y: 100), options: [])
context?.restoreGState()