Application User Authentication

Question

I have a question about user authentication when developing an iOS application. When the user launches the application, they will be prompted with the home screen which will prompt them to input a valid username and password. Once their credentials are validated they will be able to access the rest of the application. I have no idea on how to create this validation operation. I know how to create the visual portion of the application, however, anything beyond that i don't understand. In short, how do you create an application that needs credentials from the user to function?

Answer 1

First, Apple will reject your app if it cannot do something useful without authentication. Second, you collect the inputs from the user, then you will have to fire off a NSURLConnection to your server in order to authenticate, observe the response and act accordingly.

Answer 2

It depends on how your server is set up, considering you are validating with your server. You'd use NSURLConnection in somewhat this manner, this is how I do it in my own app (tailored to your parameters):

+ (NSDictionary *)executeCallWithRequest:(NSMutableURLRequest *)request {
  NSHTTPURLResponse *response = nil;
  NSError *error = nil;
  NSData *jsonData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; 
  NSString *dataString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
  error = nil;
  NSDictionary *result = jsonData ? [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves error:&error] : nil;
  if (error == nil && response.statusCode == 200) {
    NSLog(@"%i", response.statusCode);
  } else {
    NSLog(@"%@", dataString);
    NSLog(@"%@", [error localizedDescription]);
  }
  return result;
}

+ (NSDictionary *)executePostWithRequest:(NSMutableURLRequest *)request {
  request.HTTPMethod = @"POST";
  return [self executeCallWithRequest:request];
}

+ (NSDictionary *)loginUserWithCredentials:(NSDictionary *)userCredentials {
  NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@", YOUR_URL]];
  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

  NSString *requestFields = [NSString stringWithString:@""];
  for (NSString *key in [userCredentials allKeys]) {
    requestFields = [requestFields stringByAppendingFormat:@"(param name)&", key, [userCredentials objectForKey:key]];
  }

  //removes the trailing &
  requestFields = [requestFields substringToIndex:requestFields.length - 1];
  requestFields = [requestFields stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
  NSData *requestData = [requestFields dataUsingEncoding:NSUTF8StringEncoding];
  request.HTTPBody = requestData;

  return [self executePostWithRequest:request];
}

In my case I respond with a JSON encoded array.