要回答你的这个问题,I have a UIBezierPath inside my custom UIView draw(_ rect: CGRect)

function. I would like to fill the path with a gradient color.

让我们说你有一个椭圆形的路径,

let path = UIBezierPath(ovalIn: CGRect(x: 0,y: 0,width: 100,height: 100))

要创建渐变,

let gradient = CAGradientLayer()

gradient.frame = path.bounds

gradient.colors = [UIColor.magenta.cgColor,UIColor.cyan.cgColor]

我们需要一个渐变的遮罩层,

let shapeMask = CAShapeLayer()

shapeMask.path = path.cgPath

现在将此shapeLayer设置为渐变图层的蒙版,并将其作为subLayer添加到视图的图层中

gradient.mask = shapeMask

yourCustomView.layer.addSublayer(gradient)

更新

在创建渐变图层之前,使用笔划创建基础图层并添加.

let shape = CAShapeLayer()

shape.path = path.cgPath

shape.lineWidth = 2.0

shape.strokeColor = UIColor.black.cgColor

self.view.layer.addSublayer(shape)

let gradient = CAGradientLayer()

gradient.frame = path.bounds

gradient.colors = [UIColor.magenta.cgColor,UIColor.cyan.cgColor]

let shapeMask = CAShapeLayer()

shapeMask.path = path.cgPath

gradient.mask = shapeMask

self.view.layer.addSublayer(gradient)