(mask & NSEventMaskEndGesture) == NSEventMaskEndGesture is the most correct, as it handles the case where NSEventMaskEndGesture has multiple bits set.

I think, not!!

   BOOL end = !! (mask & NSEventMaskEndGesture);

Like a little pair of surprised eyes.

Also works for pointers:

    BOOL hasError = !! errorObj;

or just != 0