Swift 重构重载运算符示例解析

let c = "abc"*3;
print("c: \(c)");//c: abcabcabc

public extension String{
    static func * (lhs: String, rhs: Int) -> String {
        return String(repeating: lhs, count: rhs);
     }
}

let edg1 = UIEdgeInsets(top: 1, left: 2, bottom: 3, right: 4);
let edg2 = UIEdgeInsets(top: 4, left: 3, bottom: 2, right: 1);
let e = edg1 + edg2;

print("edg1: \(edg1)");//edg1: UIEdgeInsets(top: 1.0, left: 2.0, bottom: 3.0, right: 4.0)
print("edg2: \(edg2)");//edg2: UIEdgeInsets(top: 4.0, left: 3.0, bottom: 2.0, right: 1.0)
print("e: \(e)");//e: UIEdgeInsets(top: 5.0, left: 5.0, bottom: 5.0, right: 5.0)

public extension UIEdgeInsets{

    static func + (lhs: UIEdgeInsets, rhs: UIEdgeInsets) -> UIEdgeInsets {
        return UIEdgeInsets(lhs.top + rhs.top,
                            lhs.left + rhs.left,
                            lhs.bottom + rhs.bottom,
                            lhs.right + rhs.right
        );
     }
}