Swift returning optional value - php

Question

I'm currently working on an Xcode app that allows a user to register by sending data to my MySQL database. I just have a couple of questions.
The first question I have is on lines 10, 13, 15. I have a warning sent to me saying: "String interpolation produces a debug description for an optional value; did you mean to make this explicit?" Is there anyway I can change my code so that the value isn't optional?
Also, the response string that is sent is worded like: "responseString = Optional( This username is available)". I was planning on using the response string to display information to the user. Is there anyway that I can get rid of the parenthesis and well as the word optional?
#IBAction func TextFieldEditingDidChange(_ sender: Any) {
let request = NSMutableURLRequest(url: NSURL(string: "usernamecheck.php")! as URL)
request.httpMethod = "POST"
print("Request: \(request)")
let postString = "username=\(usernameTxt.text!)"
request.httpBody = postString.data(using: String.Encoding.utf8)
let task = URLSession.shared.dataTask(with: request as URLRequest) {
data, response, error in
if error != nil {
print("error=\(error)")
return
} // Ends errror If statements
print("response = \(response)")
let responseString = NSString(data: data!, encoding:
String.Encoding.utf8.rawValue)
print("responseString = \(responseString)")
}
task.resume()
}
portion PHP file:
$a_sql = mysqli_query($con, "SELECT username FROM users WHERE username = '" . mysqli_real_escape_string($_POST['username']) . "' ; ");
if (empty($_POST['username'])) {
$username_error = "Please input username";
} else {
$a_sql;
}
if ($a_sql && mysqli_num_rows($a_sql) > 0) {
$username_exists = "Username is already taken.";
echo $username_exists;
} else {
echo "Fail";
}

Answer 1

guard let unwrappedMessage = originalMessage else { return }
This is one of the ways to unwrap optionals but in the end it depends of what you want to do...
You should really read about optionals in Swift. It's very very easy and a beginner's topic that everyone learning Swift should learn

Answer 2

guard let message = responseString else {
return
}
print(message)
Actually, you are unwrapping an optional responsestring to message, now if it contains nil, it will not give any exception and it will fall into the else case.
On the other hand, the value will be stored in the message and can be used further

Answer 3

if let Message = Message {
print(Message)
}