很难在 swift 中实现一个简单的单例 [英] Having hard time implement a simple singleton in swift

问题描述

我创建了一个新文件 ->swift file .称为 Globals.Swift然后在那里我做了:

I have created a new file ->swift file . called Globals.Swift Then in there I have done :

class Globals {

    static let sharedInstance = Globals()

    init() {
        var max=100
    }

}

在另一个类(UIViewcontroller)中，我想使用它，

In another class(UIViewcontroller) I would like to use it,

Globals.sharedInstance //is going ok

很好，但是当我深入到 .max 时，我得到了错误.

is good, but when i go deep to .max i get the error.

推荐答案

你不能在 init 中只使用 var = xxx.变量必须在类顶层声明.

You can't just have var = xxx in an init. The variable has to be declared at the class top level.

使用单身人士的例子:

class Globals {

    static let sharedInstance = Globals()

    var max: Int

    private init() {
        self.max = 100
    }

}

let singleton = Globals.sharedInstance

print(singleton.max) // 100

singleton.max = 42

print(singleton.max) // 42

当你需要在另一个类中使用单例时，你只需在另一个类中这样做:

When you need to use the singleton in another class, you just do this in the other class:

let otherReferenceToTheSameSingleton = Globals.sharedInstance

根据 Martin R 和 Caleb 的评论进行更新: 我已将初始化程序设为私有.在其他 Swift 文件中，它阻止了 Globals() 的初始化，通过只能使用 Globals.sharedInstance 来强制此类作为单例行为.

Update following Martin R and Caleb's comments: I've made the initializer private. It prevents, in other Swift files, the initialization of Globals(), enforcing this class to behave as a singleton by only being able to use Globals.sharedInstance.

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