swift - 使结构或类可隐式转换为 String

Question

你好:)

我正在尝试构建一个自定义类型(结构或类，任何一个都适合)，其值可以在我需要时隐式转换为 String。

这是我正在寻找的示例:

public struct IKString {
    private var internalValue: String

    public init(_ value: String) {
        internalValue = value
    }
}

...

let test = IKString("Hello, world!")
myUILabel.text = test // This fails but I'm looking for a way to make it compile

这在 Swift 中可能吗？

Answer 1

class C: CustomStringConvertible {
    let property1: Int; 
    init(i: Int) {
        property1 = i
    }

    var property2: ()->() = { print("some computed property") }
    var description: String {
        return "instance of this class C has two properties: property1: \(property1) and property2: \(property2) whith type \(property2.dynamicType)"
    }
}
let c  = C(i: 100)
let s: String = c.description
print(s) // instance of this class C has two properties: property1: 100 and property2: (Function) whith type () -> ()

看见了

print(c)

给你同样的结果!

和

var text: String = ""
print(c, toStream: &text)
print(text)

将文本设置为相同的值。顺便说一下

print("\(c.property2), \(c.property2())")
// prints two lines
/*
some computed property
(Function), ()
*/

更新扩展字符串怎么样:IKString { ... } ??

struct Localisation {}
protocol IKString {
    mutating func foo()
    init(s: String, l: Localisation)
}

extension String: IKString {
    init(s: String, l: Localisation) {
        // some code
        self = s
        foo()
    }
    mutating func foo() {
        self = self.uppercaseString
    } 
}
let s2 = String(s: "blabla",l: Localisation())
print(s2) // BLABLA