Swift中的小写字典键

Question

我需要转换一个Dictionary带有混合大小写的键,Dictionary但是只能使用小写键.

这是我的尝试(它有效,但我发现这个实现非常粗糙)

extension Dictionary {
    func lowercaseKeys()->Dictionary<String, AnyObject>{
        var newDictionary = Dictionary<String,AnyObject>()

        for k in keys{
            if let k_string = k as? String{
                newDictionary[k_string.lowercaseString] = self[k] as? AnyObject
            }
        }
        return newDictionary
    }
}

你能建议一个更优雅的方法来解决这个问题吗？

Answer 1

无需临时字典即可更改自己的密钥;)

var dict = ["HEJ":"DÅ", "NeJ":"tack"]

for key in dict.keys {
    dict[key.lowercaseString] = dict.removeValueForKey(key)
}

print(dict)

[hej:DÅ,nej:tack]

编辑

我做了这个扩展,现在它有点脏,但我会再次更新它.

extension Dictionary {
    mutating func lowercaseKeys() {
        for key in self.keys {
            let str = (key as! String).lowercaseString
            self[str as! Key] = self.removeValueForKey(key)
        }
    }
}

var dict = ["HeJ":"Då", "nEJ":"taCK!"]
dict.lowercaseKeys()
print(dict)

["hej":"Då","nej":"taCK!"]

编辑2

extension Dictionary where Key: StringLiteralConvertible {
    mutating func lowercaseKeys() {
        for key in self.keys {
            self[String(key).lowercaseString as! Key] = self.removeValueForKey(key)
        }
    }
}

var dict = ["NamE":"David", "LAST_NAME":"Göransson"]

dict.lowercaseKeys() // Will compile

var dict2 = [0:"David", 0:"Göransson"]

dict2.lowercaseKeys() // Won't compile because Key isn't StringLiteralConvertible