如何创建可以在 Key 中保存任何内容的 Dictionary?或者它能够容纳的所有可能的类型 [英] How to create Dictionary that can hold anything in Key? or all the possible type it capable to hold

问题描述

我想创建一个不限制键类型的Dictionary(比如NSDictionary)

I want to create a Dictionary that does not limit the key type (like NSDictionary)

所以我尝试了

var dict = Dictionary<Any, Int>()

和

var dict = Dictionary<AnyObject, Int>()

结果

error: type 'Any' does not conform to protocol 'Hashable'
var dict = Dictionary<Any, Int>()
           ^
<REPL>:5:12: error: cannot convert the expression's type '<<error type>>' to type '$T1'
var dict = Dictionary<Any, Int>()
           ^~~~~~~~~~~~~~~~~~~~~~

好的，我会使用Hashable

var dict = Dictionary<Hashable, Int>()

但是

error: type 'Hashable' does not conform to protocol 'Equatable'
var dict = Dictionary<Hashable, Int>()
           ^
Swift.Equatable:2:8: note: '==' requirement refers to 'Self' type
  func ==(lhs: Self, rhs: Self) -> Bool
       ^
Swift.Hashable:1:10: note: type 'Hashable' does not conform to inherited protocol 'Equatable.Protocol'
protocol Hashable : Equatable
         ^
<REPL>:5:12: error: cannot convert the expression's type '<<error type>>' to type '$T1'
var dict = Dictionary<Hashable, Int>()
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~

所以Hashable继承自Equatable但不符合Equatable???没看懂...

So Hashable inherited from Equatable but it does not conform to Equatable??? I don't understand...

无论如何，继续努力

typealias KeyType = protocol<Hashable, Equatable> // KeyType is both Hashable and Equatable
var dict = Dictionary<KeyType, Int>() // now you happy?

没有运气

error: type 'KeyType' does not conform to protocol 'Equatable'
var dict = Dictionary<KeyType, Int>()
           ^
Swift.Equatable:2:8: note: '==' requirement refers to 'Self' type
  func ==(lhs: Self, rhs: Self) -> Bool
       ^
Swift.Hashable:1:10: note: type 'KeyType' does not conform to inherited protocol 'Equatable.Protocol'
protocol Hashable : Equatable
         ^
<REPL>:6:12: error: cannot convert the expression's type '<<error type>>' to type '$T1'
var dict = Dictionary<KeyType, Int>()
           ^~~~~~~~~~~~~~~~~~~~~~~~~~

我现在很迷茫，我怎样才能让编译器对我的代码满意?

I am so lost now, how can I make compiler happy with my code?

我想像这样使用字典

var dict = Dictionary<Any, Int>()
dict[1] = 2
dict["key"] = 3
dict[SomeEnum.SomeValue] = 4

<小时>

我知道我可以使用 Dictionary，但这并不是我真正想要的.

---

I know I can use Dictionary<NSObject, Int>, but it is not really what I want.

推荐答案

Swift 3 更新

您现在可以使用 AnyHashable，它是一个类型擦除的可哈希值，专为这样的场景创建:

Swift 3 update

You can now use AnyHashable which is a type-erased hashable value, created exactly for scenarios like this:

var dict = Dictionary()

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