iPad app, how to show a uiviewcontroller on top of an uiviewcontroller

Basically this is my situation and don't want to use splitview. I've a viewbased app, on a side of the main view i've to show a viewcontroller subclas开发者_开发知识库s but i don't know how to do it.

Something like this:

Even though Apple doesn't recommend it (at least on the iPhone), you can always access the view controller's view and manually add it. Like this (in MainViewController.m):

[self.view addSubView:self.secondaryViewController.view];