JSON_encode causing error when returning an array from php script to Swift

Question

In Xcode I am currently getting the following error:

Error Domain=NSCocoaErrorDomain Code=3840 "Garbage at end." UserInfo={NSDebugDescription=Garbage at end.}

This has just started happening when I added a function to my php script to retrieve 'community' details from the database. These details are stored in an array.

The following line echo json_encode($communities); appears to be causing the problem as it runs fine without it. Below is the full userLogin.php script. That line is at the bottom.

<?php

require ("Conn.php");
require ("MySQLDao.php");

$email = htmlentities($_POST["email"]);
$password = htmlentities($_POST["password"]);

$returnValue = array();


if(empty($email) || empty($password))
{
$returnValue["status"] = "error";
$returnValue["message"] = "Missing required field";
echo json_encode($returnValue);
return;
}

$secure_password = md5($password);

$dao = new MySQLDao();
$dao->openConnection();
$userDetails = $dao->getUserDetailsWithPassword($email,$secure_password);

if(!empty($userDetails))
{
$returnValue["status"] = "Success";
$returnValue["message"] = "User is registered";
echo json_encode($userDetails);
}else{

$returnValue["status"] = "error";
$returnValue["message"] = "User is not found";
echo json_encode($returnValue);
}

//once logged in run function to get list of communities

$communities = array();
$communities = $dao->getCommunities($email);
echo json_encode($communities);

$dao -> closeConnection();

?>

I have tested the SQL function in the browser and it returns the correct values, output below:

[{"name":"EnclliffeT"},{"name":"OneWinner"},{"name":"Yesss"},{"name":"Treert"},{"name":"Westbrook"}]

I'm pretty sure then that the issue is with Swift not receiving the array properly.

This is the Swift code that runs when the user logs in, which gives the error:

 @IBAction func loginButtonTapped(_ sender: AnyObject)
    {

    let userEmail = userEmailTextField.text;
    let userPassword = userPasswordTextField.text;

    if (userPassword!.isEmpty || userEmail!.isEmpty) { return; }

// send user data to server side

    let myUrl = URL(string: "http://www.quasisquest.uk/KeepScore/userLogin.php");

    var request = URLRequest(url:myUrl!);
    request.httpMethod = "POST";
    let postString = "email=\(userEmail!)&password=\(userPassword!)";
    request.httpBody = postString.data(using: String.Encoding.utf8);

    let task = URLSession.shared.dataTask(with: request) { (data: Data?, response: URLResponse?, error: Error?) in
        DispatchQueue.main.async
            {

               if(error != nil)
                {

                    //Display an alert message
                    let myAlert = UIAlertController(title: "Alert", message: error!.localizedDescription, preferredStyle: UIAlertControllerStyle.alert);
                    let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler:nil)
                    myAlert.addAction(okAction);
                    self.present(myAlert, animated: true, completion: nil)
                    return
                }

                do {

                    let json = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String:AnyObject]


                    // retrieve login details and check to see if all ok

                    if let parseJSON = json {

                        let returnValue = parseJSON["status"] as? String

                        if(returnValue != "error")
                        {
                         self.delegate?.userLoggedIn(data: userEmail! )
                         UserDefaults.set(UserDefaults.standard)(true, forKey: "isUserLoggedIn");
                         self.dismiss(animated: true, completion: nil)

                        } else {
                            // display an alert message
                            let userMessage = parseJSON["message"] as? String
                            let myAlert = UIAlertController(title: "Alert", message: userMessage, preferredStyle: UIAlertControllerStyle.alert);
                            let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler:nil)
                            myAlert.addAction(okAction);
                            self.present(myAlert, animated: true, completion: nil)
                        }

                    }
                } catch
                {
                    print(error)
                }

        }

    }

    task.resume()

}

Marc B · Accepted Answer · 2016-10-21 14:27:29Z

1

You're outputting MULTIPLE json blocks, which is illegal json:

if(!empty($userDetails))
   ...
   echo json_encode(...)
} else {
   ...
   echo json_encode(...)
}
...
echo json_encode(...)

A block of JSON text can contain only one SINGLE json structure. Since you have two, you have a JSON syntax error.

e.g.

echo json_encode('hi');
echo json_encode('mom');

produces

"hi""mom"

And since JSON IS javascript code, you're basically trying to do this:

var foo = "hi""mom";
              ^--syntax error, unexpected string

answered Oct 21, 2016 at 14:27

Marc B

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3 Comments

RDowns Over a year ago

I see. So this is because of the php script trying to output json_encode($communities); and json_encode($returnValue); ? What would be the best solution?

Marc B Over a year ago

build a SINGLE structure. $data['status'] = true; $data['message'] = 'Success'; $data['data'] = ...data you want to return, then have the client code check that status field and go from there.

RDowns Over a year ago

My aim is to carry the array across so I can display the contents in a UITableView. Would the method you mention above be suitable for that as different users would be members of differing numbers of 'communities'?

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