Trouble presenting Modal View Controller (MPMoviePlayerViewController)

My App starts up, and I have a UITabBarController. On the first tab I have a subclass of UIViewController. It's in this class that I have my movie playing functionality. I do not know why, but from this class, I cannot presentModalViewController or presentMoviePlayerViewControllerAnimated. I can however add views as a subView. I found this post, which is essentially what I'm trying to do (pres开发者_StackOverflow社区ent a movie player view controller): How to present MPMoviePlayerViewController from a UITabBarController?

But even keeping a reference to the UITabBarController does not work for me. I'm not really sure why this class has problems presenting a modal view controller, versus in other tabs, I am able to. Any thoughts? Thanks.

After more looking, I found that the problem is I cannot present a view modally within the viewDidLoad method.