将具有枚举值的Swift字典转换为NSDictionary [英] Convert Swift Dictionary With Enum Value To NSDictionary

问题描述

如果我有类型为Dictionary<String, MyEnum>的字典，则无法弄清楚如何将其转换为NSDictionary，因此可以通过NSJSONSerialize.dataWithJSONObject将其序列化为JSON.

If I have a dictionary with the type Dictionary<String, MyEnum>, I cannot figure out how to convert it to an NSDictionary so I can serialiaze it to JSON via NSJSONSerialize.dataWithJSONObject.

编译器告诉我"Dictionary<String, MyEnum> is not convertible to NSDictionary".我是否需要使用枚举的字符串值la la创建新的字典

The compiler tells me that "Dictionary<String, MyEnum> is not convertible to NSDictionary". Do I need to create a new dictionary with the string values of the enum a la

var newDict = Dictionary<String, String> (or <String, AnyObject>);
for (key, val) in oldDict {
    newDict[key] = val;
}

还是有更好的方法?

推荐答案

NSJSONSerialize和朋友只能处理与JSON本机数据相对应的NSObject子项的小子集(NSNumber，NSString，NSArray，NSDictionary和NSNull).类型.另外，如果键和值都为NSObject或固有地可转换为NSObject(字符串和数字类型)，则只能将Dictionary转换为NSDictionary.

NSJSONSerialize and friends can only deal with small subset of NSObject children (NSNumber, NSString, NSArray, NSDictionary, and NSNull) that correspond to the JSON native data types. In addition, a Dictionary can only be converted to an NSDictionary if both the key and value are NSObject or inherently convertible to NSObject (String and numeric types).

要序列化Dictionary，您需要将Enum转换为那些NSJSONSerialize数据类型之一，类似于您的示例:

In order to serialize your Dictionary you'll need to convert the Enum to one of those NSJSONSerialize data-types, similar to your example:

enum MyEnum : String {
    case one = "one"
    case two = "two"
}

let dict = ["one":MyEnum.one, "two":MyEnum.two]

var newDict = Dictionary<String, String>()
for (key, val) in dict {
    newDict[key] = val.rawValue
}

let data = NSJSONSerialization.dataWithJSONObject(newDict, options: .allZeros, error: nil)

作为一种替代方法，由于这种操作相当普遍，因此您可能需要考虑将此类别添加到Dictionary中，这为它提供了一个方便的map函数:

As an alternative, since this kind of manipulation is fairly common, you might want to consider adding this category to Dictionary, which gives it a convenient map function:

extension Dictionary {
    init(_ pairs: [Element]) {
        self.init()
        for (k, v) in pairs {
            self[k] = v
        }
    }

    func map<K: Hashable, V>(transform: Element -> (K, V)) -> [K: V] {
        return Dictionary<K, V>(Swift.map(self, transform))
    }
}

完成后，转换就很简单:

Once that's done, the conversion is simply:

let mapped = dict.map { (key, value) in (key, value.rawValue) }

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