How to prettyPrint json response from API call in debugger?

Try the JSONSerialization, something like this:

let url = URL(string: "http://date.jsontest.com")
var request : URLRequest = URLRequest(url: url!)
request.httpMethod = "GET"

let dataTask = URLSession.shared.dataTask(with: request) {
    data,response,error in
    do {
        if let jsonResult = try JSONSerialization.jsonObject(with: data!, options: []) as? NSDictionary {
            print(jsonResult)
        }
    } catch let error {
        print(error.localizedDescription)
    }
}
dataTask.resume()

Where jsonResult will print out this:

{
    date = "02-19-2018";
    "milliseconds_since_epoch" = 1519078643223;
    time = "10:17:23 PM";
}

e print(String(data: JSONSerialization.data(withJSONObject: JSONSerialization.jsonObject(with: data, options: []), options: .prettyPrinted), encoding: .utf8)!)