If you only want to save a few you might try putting bird netting around a few of the branches. I use it over the top of the soil in containers to keep them from digging in them and planting nuts so I would think it would keep them out of the apples too. Might not be practical to do it over the whole tree, but if you're willing to share the apples you could probably save some of them that way.
I don't know of any sprays unfortunately--I would think most things you could spray on them to repel squirrels would not be something you'd want to eat afterwards. Maybe hot pepper spray and wash the apples really, really thoroughly when you pick them?
1 qt spray bottle, 1/2 cup hot pepper sauce, 1/2 teas dish soap, mix well and spray the apples. Will wash off, but the little critters hate it. I have used this for many years, in the garden and on the bird feeders. they learn quickly!!!!!!! Just reapply if it rains.