Full screen dialogs should use a from-the-bottom transition, even on iOS.

My understanding is that the pattern is that things with an X button fly in from below and things with a back button fly in from the right (and have back gesture support).

Gallery > Dialogs > Fullscreen is one example.

iOS itself seems a little confused about this, since:
Settings > Personal Hotspot > Wi-Fi Password
is a dialog-like feel on iOS (has a cancel button) yet flies in from the right (as part of a navigation control.

Uber's Settings fly up from the bottom and have an X.
Inbox's Settings fly up from the bottom and have an X.
Safari Bookmarks fly up from the bottom and have a Done.
Phone > Contacts > + (new contact) flies in from the bottom and has a Done.

Etc.