Change UITextField with MySQL result (xcode project)

Question

I have three different UITextField in a "ViewController" and I would like to change these values for the ones I have in my MySQL Database. (I would like to show: followers, pictures and posts).

I know MySQL and PHP, but I'm stuck at the moment because I don't know how to do it.

First I would like to say that at the beginning, the user is going to log in using a form PHP+MySQL, maybe I have to store the username in some "var" and user later for populate those three labels with the information.

The problem is that this is my first app, and I don't know how to do it, that's why I need your help. How can I put the values from MySQL to XCode, and also, how can I store the username in a "global var" in order to use it later?

If you know any better process, please tell me, because I really want to know how to do this, because later I will have to show the profile image, profile name, etc, etc.

Edited with code:

ViewController.m

That's my login button, I will add the "load" inside the login.php file.

- (IBAction)loginClicked:(id)sender {
    @try {

        if([[_txtUsername text] isEqualToString:@""] || [[_txtPassword text] isEqualToString:@""] ) {
            [self alertStatus:@"Porfavor, introduce el usuario y contraseña" :@"Error"];
        } else {
            NSString *post =[[NSString alloc] initWithFormat:@"username=%@&password=%@",[_txtUsername text],[_txtPassword text]];
            NSLog(@"PostData: %@",post);

            NSURL *url=[NSURL URLWithString:@"http://example.com/login.php"];

            NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

            NSString *postLength = [NSString stringWithFormat:@"%lu", (unsigned long)[postData length]];

            NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
            [request setURL:url];
            [request setHTTPMethod:@"POST"];
            [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
            [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
            [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
            [request setHTTPBody:postData];

            [NSURLRequest setAllowsAnyHTTPSCertificate:YES forHost:[url host]];

            NSError *error = [[NSError alloc] init];
            NSHTTPURLResponse *response = nil;
            NSData *urlData=[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

            NSLog(@"Response code: %ld", (long)[response statusCode]);
            if ([response statusCode] >=200 && [response statusCode] <300)
            {
                NSString *responseData = [[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding];
                NSLog(@"Response ==> %@", responseData);

                SBJsonParser *jsonParser = [SBJsonParser new];
                NSDictionary *jsonData = (NSDictionary *) [jsonParser objectWithString:responseData error:nil];
                NSLog(@"%@",jsonData);
                NSInteger success = [(NSNumber *) [jsonData objectForKey:@"success"] integerValue];
                NSLog(@"%ld",(long)success);
                if(success == 1)
                {
                    NSLog(@"Login SUCCESS");
                    //[self alertStatus:@"Welcome." :@"Datos correctos"];
                    [self performSegueWithIdentifier:@"Main" sender:self];

                } else {

                    NSString *error_msg = (NSString *) [jsonData objectForKey:@"error_message"];
                    [self alertStatus:error_msg :@"Datos incorrectos"];
                }

            } else {
                if (error) NSLog(@"Error: %@", error);
                [self alertStatus:@"Ha ocurrido un problema inesperado" :@"Error"];
            }
        }
    }
    @catch (NSException * e) {
        NSLog(@"Exception: %@", e);
        [self alertStatus:@"Error." :@"Error"];
    }
}

Thanks in advance.

Answer 1

What you want to do is send an AJAX (Asynchronous JavaScript and XML) request to your server to request the information you want to display.

Server

Set up an API to deliver the information. This API will process urls like https://example.com/api.php?action=userinfo&userid=1, grab the desired information from the MySQL database send them back to the user. To send the data back, you just print the information as JSON encoded string so the client can easily process it. You could actually encode it differently as well but this is the easiest and most common way to do it.

$action = $_GET['action'];
switch ($action) {
    case "userinfo":
        $userid = $_GET['userid'];
        $data = // Grab data from sql database based on the userid
        die(json_encode(array("message" => "Getting user information succeeded.", "status" => "success", "data" => $data), JSON_PRETTY_PRINT));
    default:
        die(json_encode(array("message" => "API request failed.", "status" => "error")), JSON_PRETTY_PRINT)
}

Client

On the client side, your iOS application, you can use NSURLConnection to grab this information. Have a look at these posts on how to send a http request to your server and get the response:

• how to send Asynchronous URL Request?
• http://codewithchris.com/tutorial-how-to-use-ios-nsurlconnection-by-example/

The only thing left is converting the response from JSON string format to an xcode NSDictionary to further process in your application.

NSString *jsonString = // web server response;
NSData *JSONdata = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *jsonError = nil;
if (JSONdata != nil) { 
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:JSONdata options:0 error:&jsonError];
    if (jsonError == nil) {
        // Set your text fields here.
    }
}