Unable to extract data properly from JSON in swift - ios

Question

I have a this kind of json object in my response after parsing json string to object
[
"requestId": 1,
"response": {
code = SUCCESS;
},
"messageId": ACTION_COMPLETE
]
I am trying to extract requestId using
responseMsg["requestId"] as! Int
I am getting this error
Could not cast value of type 'NSTaggedPointerString' (0x21877a910) to
'NSNumber' (0x218788588).
I tried it changing to Int(responseMsg["requestId"] as! String)!
This thing is working for positive numbers but not for negative numbers probably bcz when requestId = -2 it throws me an error
Could not cast value of type '__NSCFNumber' (0x21877a000) to
'NSString' (0x218788290).
I tried with different other solution too but did not work.

Answer 1

For parsing the JSON data, its better use Codable instead of manually parsing everything.
For JSON format,
{
"requestId": 1,
"response": {
"code":"SUCCESS"
},
"messageId": "ACTION_COMPLETE"
}
Create Models like,
struct Root: Decodable {
let requestId: String?
let messageId: String
let response: Response
enum CodingKeys: String, CodingKey {
case requestId, messageId, response
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
if let id = try? values.decode(Int.self, forKey: .requestId) {
requestId = String(id)
} else if let id = try? values.decode(String.self, forKey: .requestId) {
requestId = id
} else {
requestId = nil
}
messageId = try values.decode(String.self, forKey: .messageId)
response = try values.decode(Response.self, forKey: .response)
}
}
Now, parse the JSON data using,
do {
let root = try JSONDecoder().decode(Root.self, from: data)
print(root.requestId) //access requestId like this....
} catch {
print(error)
}

Answer 2

Try
Int(String(describing: responseMsg["requestId"]))!
This ensures any data is converted to string first and then to int

Answer 3

This error message
Could not cast value of type 'NSTaggedPointerString' (0x21877a910) to 'NSNumber' (0x218788588).
tells us that the JSON request id is being parsed as a string. NSTaggedPointerString is a special internal type used by the ObjC runtime to represent strings.
Try this:
let requestId = responseMsg["requestId"] as! String
print("request id: \(requestId)") // Prints a string
Note, it may print something that looks like a number, but it isn't one.
The JSON you are parsing probably looks like
{
"requestId": "1",
"response": {
"code" = "SUCCESS"
},
"messageId": "ACTION_COMPLETE"
}
Note the 1 in quotes.

Answer 4

Swift 5
String interpolation is what worked for me! (casting it first to String didn't work as I had other values for which the json decoder actually did its job and cast them directly to a number)
if let responseMsg_any = responseMsg["requestId"],
let responseMsg_int = Int("\(responseMsg_any)") {
//..
}
Warning:
This solution allows any Type to become a String and be checked for a Int value. Only use this if you're not concerned about the value's Type prior to interpolation.