//  字典转json
var dict = ["男":"杰克","女":"萝丝"]

if (JSONSerialization.isValidJSONObject(dict)){
    let jsonData:NSData = try JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted) as NSData
    let  json:String = (NSString(data:jsonData as Data, encoding:String.Encoding.utf8.rawValue))! as String
    
    print(json)
    
    //  json转字典
    let dict1 = try  JSONSerialization.jsonObject(with:jsonData as Data, options: .mutableContainers) as! NSDictionary

    print(dict1)
    
    let value02 = dict1["男"]!;
    print(value02)
}

输出为：

{
  "男" : "杰克",
  "女" : "萝丝"
}
{
    "\U5973" = "\U841d\U4e1d";
    "\U7537" = "\U6770\U514b";
}
杰克