Pat,
Sorry but replacing most of their diet would not be good.
Your weaners need protein to grow muscle (ie meat), so need to get this from their pig nuts. The apples would make a good supplement, but not a replacement.
For your sows, we are loking at maintenance and you could get away with maybe 1/3 or even replace one meal a day for a short while, but such a pure alternative (as opposed to say waste fruit and veg with more varied nutrients) is not good long term, and maybe you should take less than two tons, or compost what goes bad before you feed. You may also find that your pigs go squity!
Don't let me put you off feeding these, we are currently feeding small amounts of windfall apples to our sows each day.