为什么数组是Swift中的AnyObject？ [英] Why is an Array an AnyObject in Swift?

问题描述

我无法理解AnyObject的局限性。

I'm having trouble understanding the limitations of AnyObject.

您可以从标题中看到Array是一个结构体。然而，此代码的工作：

You can see from the header that Array is a struct. Nevertheless, this code works:

var whatobject : AnyObject
whatobject = [1,2]

和它不只是文字数组：

var whatobject : AnyObject
let arr = [1,2,3]
whatobject = arr

但是，我无法为 whatobject 指定一个结构：

However, I can't assign a struct that I make to whatobject:

struct S {}
var whatobject : AnyObject
whatobject = S() // error

所以数组毕竟不是一个结构？

So an array isn't really a struct after all?

推荐答案

当桥接进入时，这是有趣的部分......

that's the fun part when bridging comes in...

默认情况下，Swift bridge

by default, Swift bridge

• Int （和朋友）到 NSNumber


• 字符串到 NSString


• 字典来的NSDictionary

• Int (and friends) to NSNumber
• String to NSString
• Dictionary to NSDictionary

所以编译器将改变它们到对象如果NEE d到

so compiler will change them to object if need to

你可以做到

var num : AnyObject = 1 // I think num is now NSNumber
var arr : AnyObject = [1,2,3] // I think arr is now NSArray of @[@1,@2,@3]

---

您无法分配 sturct / 枚举来 AnyObject ，因为它们不是对象类型（可以使用任何来持有它们）

---

and you can't assign sturct/enum to AnyObject because they are not object type (you can use Any to hold them)

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