iOS如何在storyboard和xib中设置UIView的图层

UIView图层常用属性：

• 边角半径
• 阴影色及偏移
• 阴影透明度
• 边框粗细和颜色

扩展UIView

import UIKit

extension UIView {
    
    //圆角半径
    @IBInspectable
    var cornerRadius: CGFloat {
        get {
            return layer.cornerRadius
        }
        set {
            layer.cornerRadius = newValue
        }
    }
    
    //阴影圆角半径
    @IBInspectable
    var shadowRadius: CGFloat {
        get {
            return layer.shadowRadius
        }
        set {
            layer.shadowRadius = newValue
        }
    }
    
    //阴影透明度
    @IBInspectable
    var shadowOpacity: Float {
        get {
            return layer.shadowOpacity
        }
        set {
            layer.shadowOpacity = newValue
        }
    }
    
    //阴影颜色
    @IBInspectable
    var shadowColor: UIColor? {
        get {
            return layer.shadowColor != nil ? UIColor.init(cgColor: layer.shadowColor!) : nil
        }
        set {
            layer.shadowColor = newValue?.cgColor
        }
    }
    
    //阴影偏移
    @IBInspectable
    var shadowOffset: CGSize {
        get {
            return layer.shadowOffset
        }
        set {
            layer.shadowOffset = newValue
        }
    }
}

这样就可以直接在storyboard和xib中设置UIView的图层属性