FDRotationGestureRecognizer

A UIGestureRecognizer subclass that, once added to a view, allows to easily measure the rotation performed by the user dragging on the screen.

Demo

This is just a little demo built around the gesture recognizer:

(Video available here if you don't like gifs.)

How it works

Basically when the user starts the gesture, the initial tap coordinates are recorded and, as the gesture continues, the angle is updated as explained in this image.

Credits

I created this component while building the MyFertility app to implement the circular day picker. Thanks to @dzamir and Return Service for letting me open source it :)