Study

1) http://abhijeetbargeios.blogspot.in/

2) https://www.codementor.io/mattgoldspink/ios-interview-tips-questions-answers-objective-c-du1088nfb

Generting ipa file to link.

https://www.diawi.com

Download ipa use:
www.i.diawi.com

Convert from Objective c to Swift:
https://objectivec2swift.com/#/home/converter/