Swift 等价于 Java toString() [英] Swift equivalent of Java toString()

问题描述

用于打印类实例状态的 Java toString() 的 Swift 等价物是什么?

What is the Swift equivalent of Java toString() to print the state of a class instance?

推荐答案

description 属性正是您要寻找的.这是打印包含对象的变量时访问的属性.

The description property is what you are looking for. This is the property that is accessed when you print a variable containing an object.

您可以通过采用协议 CustomStringConvertible 然后实现 description 属性，将 description 添加到您自己的类中.

You can add description to your own classes by adopting the protocol CustomStringConvertible and then implementing the description property.

class MyClass: CustomStringConvertible {
    var val = 17

    public var description: String { return "MyClass: \(val)" }
}

let myobj = MyClass()
myobj.val = 12
print(myobj)  // "MyClass: 12"

description 也用于调用 String 构造函数:

description is also used when you call the String constructor:

let str = String(myobj)  // str == "MyClass: 12"

这是访问实例描述的推荐方法(与 myobj.description 相反，如果类没有实现 CustomStringConvertible，它将不起作用)

This is the recommended method for accessing the instance description (as opposed to myobj.description which will not work if a class doesn't implement CustomStringConvertible)

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