UINavigationContoller : コードで画面遷移する

// nextViewControllerへ遷移
[self.navigationController pushViewController:nextViewController animated:YES];

// 前の画面に戻る
[self.navigationController popViewControllerAnimated:YES];

// TOP画面に戻る
[self.navigationController popToRootViewControllerAnimated:YES];

// 特定のViewControllerに戻る
[self.navigationController popToViewController:displayViewController animated:YES];