JSONSerialization

Data转字典

let data = jsonStr.data(using: String.Encoding.utf8)
let result:[String:Any] = try! JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as! [String : Any]

字典转Data

let dict = ["aaa":111, "bbb":222, "ccc":333]

let jsonData = try! JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)