What to do for iOS applications development?
learn iOS programming language
First of all, a Macbook and Basic understanding of Objective-C.
Getting started with IOS Development : http://www.hongkiat.com/blog/ios-development-guide-part1/
you must have good knowledge of c and oops concepts.Rest you can start with objective C or swift. I would recommend you to start with objective C because you can find more help online in objective C rather than swift