通过纯代码加载

UIViewController *targetVC = [PFTargetVC alloc] init];
[self.navigationController pushViewController:targetVC animated:YES];

通过storyboard加载

// 获取storyboard
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
// 根据storyboard获取控制器实例
UIViewController *targetVC = [storyboard instantiateViewControllerWithIdentifier:@"IDENTIFIER"];
[self.navigationController pushViewController:targetVC animated:YES];

通过xib加载

UIViewController *targetVC = [[UIViewController alloc] initWithNibName:@"NIBNAME" bundle:nil];
[self.navigationController pushViewController:targetVC animated:YES];