Please give me some tasks to train my programming skills in: recursion, pointers and at lasts Objective-C.

Answer 1

Or you can redo the courses if you haven't
Nooe do the course first.
https://www.sololearn.com/Course/Cplusplus/?ref=app

Answer 2

Yep, codewars is great for sharpening your skills. I wish sololearn had something similar, there's just nothing to do here.