Ipa file size issue

I'm new in IOS development. I got problem with my .ipa file. I don't use any pod library, and my assets folder size is 5.6 MB. But when I export my .ipa file , it becomes 66 MB. How can I decrease the size of my .ipa file? I imported only SWRevealController class. It's a simple app (Also I use 6 NavigationController classes). Is it normal? How can I fix that?