如何处理从HTTP GET请求返回的JSON-Swift？

Question

This is my code :

        let myUrl = NSURL(string:"hostname/file.php");

    let request = NSMutableURLRequest(URL:myUrl!);
    request.HTTPMethod = "GET";


    NSURLSession.sharedSession().dataTaskWithRequest(request, completionHandler: { (data:NSData?, response:NSURLResponse?, error:NSError?) -> Void in

        dispatch_async(dispatch_get_main_queue())
            {



                if(error != nil)
                {
                    //Display an alert message

                    return
                }



                do {
                    let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as? NSDictionary

                    if let parseJSON = json { /* when the app reach here , will enter the catch and get out */

                        let userId = parseJSON["id"] as? String
                        print(userId)

                        if(userId != nil) 
                        {

                            NSUserDefaults.standardUserDefaults().setObject(parseJSON["id"], forKey: "id")
                            NSUserDefaults.standardUserDefaults().setObject(parseJSON["name"], forKey: "name")

                            NSUserDefaults.standardUserDefaults().synchronize()


                        } else {
                            // display an alert message
                                print("error")

                        }

                    }
                } catch
                {
                    print(error)
                }


        }



    }).resume()

my app getting the JSON from php file that parse the array from database into JSON and return it using echo and it return the following 2 rows :

[{"id":"1","name":"CIT","adminstrator_id":"1"},{"id":"2","name":"HelpDesk","adminstrator_id":"1"}]

When I print description of json I get nil

I tried to cast the json to NSArray , when I print first json[0] I get the first row which is good but when I tried to cast result of json[0] to NSDictionary still I'll get nil from it

when the app reach the if statement if let parseJSON = json it will enter the catch and it's not printing any error , I don't know why ?

this my php code :

    <?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "mydb";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
$sql = "SELECT * FROM department";
$result = $conn->query($sql);
$rows = array();
if ($result->num_rows > 0) {
    // output data of each row
    while($r = $result->fetch_assoc()) {
        $rows[] = $r;
    }
    $conn->close();
    echo json_encode($rows);
} else {
    $conn->close();
    echo "0 results";
}
?>

So is the problem in my request or with handling the request ?

Answer 1

The JSON is an array of [String:String] dictionaries.

In a JSON string [] represents an array and {} represents a dictionary.

An URLRequest is not needed because GET is the default mode. .MutableContainers is not needed either because the values are only read.

Consider that the JSON returns multiple records. This code just prints all values for id and name .

let myUrl = NSURL(string:"hostname/file.php")!
NSURLSession.sharedSession().dataTaskWithURL(myUrl) { (data, response, error) in
  if error != nil {
    print(error!)
  } else {
    do {
      if let json = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? [[String:String]] {
        for entry in json {
          if let userId = entry["id"], name = entry["name"] {
            print(userId, name)
          }
        }
      } else {
        print("JSON is not an array of dictionaries")
      }
    } catch let error as NSError {
      print(error)
    }
  }
}.resume()