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// Example JSON
var JSON = "{\n" +
    "\"name\": \"Ali\",\n" +
    "\"surname\": \"Batur\",\n" +
    "\"age\":29\n" +
"}"

// Convert json string to data. JSON string is the response from restfull call.
var data: Data = JSON.data(using: .utf8)!

// Convert data to Dictionary
let personDictionary = try! JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any]

// If you will not map this person dictionary, you will use it like this;
nameLabel.text = personDictionary["name"] ?? "" // defaut value 

// What if I want you to combine name and surname, I mean put some little business for your class. 
// In the case of not using mapping you would do this like this:
let name = personDictionary["name"] ?? "" // defaut value 
let surname = personDictionary["surname"] ?? "" // defaut value 
let fullname = "\(name) \(surname)"
fullnameLabel.text = fullname

// This will work ofc. But without mapping, you should handle any case of error at your response block, your business will be at response block.
// I gave this example, because some code reviews I did, show me the usage of this style.