iOS: present view controller programmatically

I'm using the presentViewController:animated:completion: method to go to another view controller.

This is my code:

AddTaskViewController *add = [[AddTaskViewController alloc] init];
[self presentViewController:add animated:YES completion:nil];

This code goes to the other UIViewController but the other controller is empty. I've always been using storyboards but now I need this to be done in code.