给view添加阴影

ViewShadow.swift

public extension UIView {
    /// 添加阴影效果
    func setShadow(color: UIColor = UIColor.black, opacity: Float = 0.5, offset: CGSize = CGSize(width: 0, height: 0)) {
        // 添加阴影
        self.layer.shadowColor = color.cgColor
        // 阴影的透明度
        self.layer.shadowOpacity = opacity
        // 阴影的偏移
        self.layer.shadowOffset = offset
        // 避免离屏渲染带来卡顿
        self.layer.shadowPath = UIBezierPath(rect: bounds).cgPath
    }
}