iOS URLSession Error "JSON text did not start with array or object and option to allow fragments not set."

Question

I'm currently on a project where I have to submit some data to PHP file and get the return from PHP.

Problem

When I try to do that using iOS URLSession, I'm getting an error,

The data couldn’t be read because it isn’t in the correct format.
Error Domain=NSCocoaErrorDomain Code=3840 "JSON text did not start with array or object and option to allow fragments not set." 
UserInfo={NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}

Because of this error, I made a sample php file where I return the value which I sent from Swift. And still getting this error along with some additional information.

<NSHTTPURLResponse: 0x60400042e200> { URL: http://192.168.1.99/insertDataTest.php } { status code: 200, headers {
Connection = "Keep-Alive";
"Content-Length" = 5;
"Content-Type" = "application/json";
Date = "Thu, 07 Dec 2017 09:55:58 GMT";
"Keep-Alive" = "timeout=5, max=100";
Server = "Apache/2.4.10 (Raspbian)";

} }

What I've done so far

Here I know the content coming from the PHP, cannot be read by Swift. I'm sending a 5 digit string from Swift to PHP and since I'm returning it without doing anything, I'm getting length of 5 data. Also I manually added a code to php in orders to made header as application/json. But still getting this error. I'm sending json encoded data from PHP as well.

My Code

Swift:

let postParameters = "{\"usermobilenum\":12345}"
request.httpBody = postParameters.data(using: String.Encoding.utf8)
let task = URLSession.shared.dataTask(with: request as URLRequest)
{
    data, response, error in
    if error != nil
    {
      print("error is \(String(describing: error))")
      return;
    }

    do
    {
      print(response!)
      let myJSON = try  JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
      if let parseJSON = myJSON
      {
          var msg : String!
          msg = parseJSON["message"] as! String?
          print(msg)

      }
    }
    catch
    {
      print(error.localizedDescription)
      print(error)
    }

}
task.resume()

PHP :

<?php
header("Content-Type: application/json");
if($_SERVER["REQUEST_METHOD"]=="POST")
{
    $data =json_decode(file_get_contents('php://input'),true);
    $userPhone = $data["usermobilenum"];
    echo json_encode($userPhone);
    mysqli_close($connect);
}
else
{
    echo json_encode("Failed in POST Method");
}

?>

I have no idea what this causes. I did try to find a solution for this in the internet and had no luck. Please help here. I'm using the latest Swift version.

Samitha Nanayakkara · Accepted Answer · 2017-12-07 12:09:44Z

2

Luckily I found the solution for my own problem. I missed to understand the error. As it says "option to allow fragments not set.", What I did was adding option .allowFragments. So the whole line after this replacement,

let myJSON = try  JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? NSDictionary

And I could solve the problem and get the answer PHP returns.

answered Dec 7, 2017 at 12:09

Samitha Nanayakkara

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1 Comment

CamQuest Over a year ago

I get "JSON text did not start with array or object and option to allow fragments not set." when I am missing a semicolon in my PHP file. Debugging needed to be done using a browser, not from Xcode.

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