I think that one of the most common deceptions for iOS developers is to discover how small is the set of default transitions that the iOS SDK support out of the box. There are just four of them: flip from left or right, and curl up or down. Well, I also think that all iOS developers also think that those four are simply the only <i>public</i> transitions in the SDK, but that there have to be more. But, you know, non public means rejection, a word that no one likes.
Lately, thank to this post by Benjamin Godard, I have not only discovered that indeed there are more transitions, but that there is also a way to safely use them – i.e., without your app being rejected. On this page you can find a list of all the numerical constant values that are associated to several default transitions that are there for your to use. Using the numerical code should be App-Store-safe, since no symbol is involved.