Question

我有一系列字典，我想转换为JSON。我的对象是[[String: AnyObject]]类型，并希望最终得到这样的示例：

[
  { "abc": 123, "def": "ggg", "xyz": true },
  { "abc": 456, "def": "hhh", "xyz": false },
  { "abc": 789, "def": "jjj", "xyz": true }
]

这就是我正在尝试的，但编译器并不喜欢我的声明：

extension Array where Element == Dictionary<String, AnyObject> {
    var json: String {
        do { return try? NSJSONSerialization.dataWithJSONObject(self, options: []) ?? "[]" }
        catch { return "[]" }
    }
}

我该怎么做？

Answer 1

实现这一目标的一种简单方法是扩展CollectionType。

使用可选的绑定和向下转换，然后序列化为数据，然后转换为字符串。

extension CollectionType where Generator.Element == [String:AnyObject] {
    func toJSONString(options: NSJSONWritingOptions = .PrettyPrinted) -> String {
        if let arr = self as? [[String:AnyObject]],
            let dat = try? NSJSONSerialization.dataWithJSONObject(arr, options: options),
            let str = String(data: dat, encoding: NSUTF8StringEncoding) {
            return str
        }
        return "[]"
    }
}

let arrayOfDictionaries: [[String:AnyObject]] = [
    ["abc":123, "def": "ggg", "xyz": true],
    ["abc":456, "def": "hhh", "xyz": false]
]

print(arrayOfDictionaries.toJSONString())

输出：

[
  {
    "abc" : 123,
    "def" : "ggg",
    "xyz" : true
  },
  {
    "abc" : 456,
    "def" : "hhh",
    "xyz" : false
  }
]

Answer 2

Swift 4 ：

extension Collection where Iterator.Element == [String:AnyObject] {
    func toJSONString(options: JSONSerialization.WritingOptions = .prettyPrinted) -> String {
        if let arr = self as? [[String:AnyObject]],
            let dat = try? JSONSerialization.data(withJSONObject: arr, options: options),
            let str = String(data: dat, encoding: String.Encoding.utf8) {
            return str
        }
        return "[]"
    }
}

<强>用法：

let arrayOfDictionaries = [
  { "abc": 123, "def": "ggg", "xyz": true },
  { "abc": 456, "def": "hhh", "xyz": false },
  { "abc": 789, "def": "jjj", "xyz": true }
]

print(arrayOfDictionaries.toJSONString())

Answer 3

我认为您在尝试扩展Array时运气不佳，因为在扩展实体时无法实现相同类型的要求。

你可以做的是利用免费功能：

func jsonify(array: [[String:AnyObject]]) { 
...
}

通过这种方式，您可以保持所需的类型安全，但需要花费移动功能位置。

Answer 4

Swift 5，我不得不将其更改为 Any 而不是 AnyObject，构建了 Eric & A.G. 的解决方案

extension Collection where Iterator.Element == [String: Any] {
  func toJSONString(options: JSONSerialization.WritingOptions = .prettyPrinted) -> String {
    if let arr = self as? [[String: Any]],
       let dat = try? JSONSerialization.data(withJSONObject: arr, options: options),
       let str = String(data: dat, encoding: String.Encoding.utf8) {
      return str
    }
    return "[]"
  }
}

用法：

let arrayOfDictionaries = [
  { "abc": 123, "def": "ggg", "xyz": true },
  { "abc": 456, "def": "hhh", "xyz": false },
  { "abc": 789, "def": "jjj", "xyz": true }
]

print(arrayOfDictionaries.toJSONString())

如何将字典数组转换为JSON？

4 个答案: