Don't leave apple as a log, it will really check and split. If the grain is straight, it will split straight.
If it doesn't split straight it was never going to make a bow any way. Look at the bark for clues to the straightness of the grain.
None of the apple I've split twisted during drying either(large logs,not brances or saplings). Checking was the only problem, so seal the underbark surface with a couple of coats of glue when you take the bark off.