Myujth

I've a big json data. I'm trying to describe the scenario below ->

JSON = 

"str1": 1,

"str2": false,

"response":

 
 "str1": 10.2,

 "lists": [
 "list": ["a", "b", "c"],
 "something": 1
 , 
 "list": ["a1", "b1", "c1"],
 "something": 2
 ]

 

I get this json from server as [String : Any]

var jsonData: Any?

func firstInitialiseJsonData(jsonData: Any?) // Initialize jsonData by server json
 self.jsonData = jsonData

Now I want to update this self.jsonData.

func updateJsonData() 
 guard let newJsonData = self.jsonData as? [String : Any] else return 
 guard let response = newJsonData["response"] as? [String : Any] else return 
 guard var lists = response["lists"] as? [[String : Any]] else return 

 lists.append(["list": ["a2","b2","c2"], "something" : 3])

But above code is not working, because "lists" contains copy data. How can I update self.jsonData? Any Help

But above code is not working, because "lists" contains copy data. How can I update self.jsonData?

I'd do it by reassigning each of the pieces back to the container from whence they came. I don't have time to test the following code right now, so watch out for errors, but this should at least illustrate the idea:

func updateJsonData() 
 guard var newJsonData = self.jsonData as? [String : Any] else return 
 guard var response = newJsonData["response"] as? [String : Any] else return 
 guard var lists = response["lists"] as? [[String : Any]] else return 

 lists.append(["list": ["a2","b2","c2"], "something" : 3])
 response["lists"] = lists
 newJsonData["response"] = response
 self.jsonData = newJsonData

In a value type environment you have to assign the mutated object back. This is very cumbersome when using primitive collection types.

With custom structs and Decodable it's much more convenient (and efficient)

This example omits all irrelevant keys

let json = """

 "str1": 1,
 "str2": false,
 "response": 
 "str1": 10.2,
 "lists": [
 "list": ["a", "b", "c"],
 "something": 1
 , 
 "list": ["a1", "b1", "c1"],
 "something": 2
 ]
 

"""

struct Root : Decodable 
 var response : Response


struct Response : Decodable 
 var lists : [List]


struct List : Decodable 
 let list : [String]
 let something : Int

let data = Data(json.utf8)

do 
 // decode the JSON to the `Root` struct, `var` makes the object mutable
 var jsonData = try JSONDecoder().decode(Root.self, from: data)
 // create a new `List`
 let newList = List(list: ["a2","b2","c2"], something: 3)
 // assign the value back to the top level object
 jsonData.response.lists.append(newList)

 print(jsonData)

 catch 
 print(error)