create a drop down menu iOS

Hi. I have been searching the internet on steps to creating a drop down menu for an iPad/iPhone app I am working for. I want to have a drop down menu when the user clicks on a button on the title or navigation bar which will contain buttons that will allow them to navigate to other viewcontrollers. Has any one been successful in developing a drop down menu and if so how did you do it? My internet search as not been successful. Some good examples are such as the facebook app or the maps app on iOS 6 that has three buttons on the bottom when you want to view the driving instructions for traveling from starting point to destination point.

Thank you for your help in advance.