swift – 如何创建可以在Key中保存任何内容的字典?或者它能够保
发布时间:2020-12-14 06:07:18 所属栏目:百科 来源:网络整理
导读:我想创建一个不限制键类型的字典(如NSDictionary) 所以我试过 var dict = DictionaryAny,Int() 和 var dict = DictionaryAnyObject,Int() 结果 error: type 'Any' does not conform to protocol 'Hashable'var dict = DictionaryAny,Int() ^REPL:5:12: error
我想创建一个不限制键类型的字典(如NSDictionary)
所以我试过 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 '$T1' var dict = Dictionary<Any,Int>() ^~~~~~~~~~~~~~~~~~~~~~ OK,我将使用Hashable var dict = Dictionary<Hashable,Int>() 但 error: type 'Hashable' does not conform to protocol 'Equatable' var dict = Dictionary<Hashable,Int>() ^ Swift.Equatable:2:8: note: '==' requirement refers to 'Self' type func ==(lhs: Self,rhs: Self) -> Bool ^ Swift.Hashable:1:10: note: type 'Hashable' does not conform to inherited protocol 'Equatable.Protocol' protocol Hashable : Equatable ^ <REPL>:5:12: error: cannot convert the expression's type '<<error type>>' to type '$T1' var dict = Dictionary<Hashable,Int>() ^~~~~~~~~~~~~~~~~~~~~~~~~~~ 所以Hashable继承自Equatable,但它不符合Equatable ???我不明白… 反正,不断尝试 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,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>() ^~~~~~~~~~~~~~~~~~~~~~~~~~ 我现在这么迷路,我怎么能让编译器满意我的代码? 我想使用字典 var dict = Dictionary<Any,Int>() dict[1] = 2 dict["key"] = 3 dict[SomeEnum.SomeValue] = 4 我知道我可以使用Dictionary< NSObject,Int>,但它不是我真正想要的。
我相信,从Swift 1.2,你可以使用ObjectIdentifier结构体。它实现了Hashable(因此Equatable)以及Comparable。您可以使用它来包装任何类实例。我猜测的实现使用包装对象的底层地址为hashValue,以及在==运算符内。
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