Yes, I miss the Back button functionality on Android, but I don't think it would be an elegant fit into the iOS way of doing things.
I too love being able to swipe to go back a screen in most iOS apps, but the thing with Android is the Back button would also go back whole apps at a time. If you tap on a link in Twitter (or whatever) for example, it might open the link in Chrome, then tapping Back takes you back to Twitter again (if I remember correctly). It worked on a stack of open apps, backtracking through all your steps, rather than just going back screens in the current app.