Swift 无法解析的json中unicode的问题（\u）

使用Foundation的JSONSerialization解析带有unicode的json 字符串时，报错如下：

Printing description of error:
Error Domain=NSCocoaErrorDomain Code=3840 "Unexpected end of file during string parse (expected low-surrogate code point but did not find one)." UserInfo={NSDebugDescription=Unexpected end of file during string parse (expected low-surrogate code point but did not find one).}

解析出错的json如下：

{
   "zhid": null,
   "orderTime": "4小时前",
   "nickName": "仙***\uDF19",
   "userAvatar": "http://auth2.xunbaotianxing.com/authimg/avatar/2202222685.png",
   "orderNum": 191159,
   "orderDesc": "【新鲜水果】【黄金瓜】 x1.0份 ¥17.55份（1个/份，约2-2.5斤）\n【新鲜水果】【红颜草莓】 x4.0份 ¥16.0份（400g/份）\n【新鲜水果】【小台芒】 x2.0份 ¥7.8份（1斤/份）\n【新鲜水果】【沃柑散装】 x3.0份 ¥7.5份（1斤/份）"
  }

仙***\uDF19这段文本中有unicode 编码，无法正常解析，

解决方案：
CFStringTransform 可以解决转换unicode 编码， 其可以在拉丁语和阿拉伯语、西里尔语、希腊语、韩语（韩国）、希伯来语、日语（平假名和片假名）、普通话、泰语之间来回转写。
通过其进行转换

func unicodeString(_ str: String) -> String {
    let mutableStr = NSMutableString(string: str) as CFMutableString
    CFStringTransform(mutableStr, nil, "Any-Hex/Java" as CFString, true)
    return mutableStr as String
}

将json 字符串 通过CoreFoundation中的CFStringTransform 转码，然再通过JSONSerialization解析：

func test() {
    do {
        let data = try Data.init(contentsOf: URL(fileURLWithPath: "jsontest.json"), options: .alwaysMapped)
        if let str = String(data: data, encoding: .utf8), let data = str.data(using: .utf8)
        {
            do {
                let obj = try JSONSerialization.jsonObject(with: data, options: .fragmentsAllowed)
                print(obj)
            } catch {
                print("error")
            }
        }
        
    } catch  {
        print("error")
    }
}

或者使用swift标准库的String的方法:

@available(OSX 10.11, iOS 9.0, *)
    public func applyingTransform(_ transform: StringTransform, reverse: Bool) -> String?

解析：

func test() {
    do {
        let data = try Data.init(contentsOf: URL(fileURLWithPath: "jsontest.json"), options: .alwaysMapped)
        if let str = String(data: data, encoding: .utf8)
        {
            guard let transformStr = str.applyingTransform(StringTransform(rawValue: "Any-Hex/Java"), reverse: true) else {
                return
            }
            let data = transformStr.data(using: .utf8)
            do {
                let obj = try JSONSerialization.jsonObject(with: data!, options: .fragmentsAllowed)
                print(obj)
            } catch {
                print("error")
            }
        }
        
    } catch  {
        print("error")
    }
}