Loading different class's view on button press

I have a class with nib file. On that nib file i put a button.

I want when somebody press that button it take you to another class's view i.e. nib file.

I have tried this

FormController *cont开发者_Python百科roller = [[FormController alloc] initWithNibName:@"countriesViewController" bundle:nil];

[self.navigationController pushViewController:controller animated:YES];