[移动开发]Swift Tips | 小技巧

1、override property ｜ 重写属性

class A {
	var property = false
}

class B: A {
    override var property: Bool {
        get {
            return true
        }
        set {
            super.property = newValue
        }
    }
   } 

2、make a exact duplicate copy of an array

var arr = [1, 2, 3]
var arrCopy = arr.map { $0.copy() }

3、 test equality of Swift enums with associated values

// Before Swift 4.1
enum SimpleToken: Equatable {
    case Name(String)
    case Number(Int)
}

public func ==(lhs: SimpleToken, rhs: SimpleToken) -> Bool {
    switch (lhs, rhs) {
    case let (.Name(a),   .Name(b)),
         let (.Number(a), .Number(b)):
      return a == b
    default:
      return false
    }
}

// Swift 4.1+
enum SimpleToken: Equatable {
    case Name(String)
    case Number(Int)
}