Handle JSON response data and String response data respectively in callback

Question

My backend can either return JSON or plain string data in response.

let task = session.dataTask(with: request as URLRequest) { data, response, error in
    if error == nil {
       // Handle response data, but it could be JSON & it could also be String data, how to check and distinguish & handle respectively?
       if let data = data {
                // it fails here if the data is String
                if let jsonDataDict = try? JSONSerialization.jsonObject(with: data) as? JSONDataDict {

                } else {
          }

    }
}

In the response callback, how to check wither the response data is JSON format or String , how to handle respectively?

Answer 1

Try with String initialiser passing data an UTf8 as string encoding

if let data = data {
                // it fails here if the data is String
                if let jsonDataDict = try? JSONSerialization.jsonObject(with: data) as? JSONDataDict {

                } else {
                if let dataString = String(data: data, encoding: .utf8){
                      debugPrint(dataString)
                }
          }

    }

Answer 2

 let jsonDataDict = try? JSONSerialization.jsonObject(with: data) as? JSONDataDict

 if let strJSON = jsonDataDict as? [String:String] //you can cast in string as
 {
    if strJSON?.isEmpty == false {
        //It is empty
    } 

 }

Answer 3

if let data = data {
        if data is Data {
            //do operation with Data
            if let jsonDataDict = try? JSONSerialization.jsonObject(with: data) as? JSONDataDict {
            }
        }
        else if data is String {
            //do operation with string
        }
    }

AppleDoc

Use the type check operator (is) to check whether an instance is of a certain subclass type. The type check operator returns true if the instance is of that subclass type and false if it is not.