如果加载数据完成，请加载View

Question

我以编程方式更改视图：

 UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    UIViewController *vc = [storyboard instantiateViewControllerWithIdentifier:@"edit"];
    vc.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
    [self presentViewController:vc animated:YES completion:nil];

问题是，当我更改视图时，数据未完全加载。我怎么说，它应该等待，直到数据被加载？