Weird encoding in executable files in ios apps
iOS applications consist of compiled code and additional support files, you would need decompilation tools of some kind to get back from the compiled code to readable source. As a starter see


IPA File Format
.ipa (file extension)
Bundle Programming Guide/Bundle Structures


If you just want to understand how iOS apps are developed you might be better of by looking at sample code within Apple's Developer Documentation and/or some of the various online repositories/courses.