Strategy - Drawing a 'correct tick/check mark' to perform an action

Question

I am looking for a strategy or guidance to get the functionality. I have a an app that does simple math. A math sum such as "4+4 = 8" appears, and if the user agrees they draw a "tick" or "correction mark" (similar to the Nike tick) or if they dont agree they draw an "X".

I know how to draw however what is the technique to detect if either the tick or the X has been drawn? Or simpler, just detect if the "tick" is indeed a tick.

It is just guidance and/or direction to find a solution that will recognise these using UIGestureRecognizer.

Answer 1

Custom gestures are possible using UIGestureRecognizer. I'm not sure how to do it as I never have before. But here is a good tutorial on the different options available.

Tutorial

Also this answer.

And this answer.