The good news is, you most likely won’t have to fight them off from apples. Due to their carnivorous appetites, cats lack taste receptors for sweetness so they won’t be too excited by a sweet treat of any type, including apples!
The truth of the matter is, fruits are not part of a cat’s natural diet. Cats are carnivorous and having too much sugar (yes, even natural sugar found in fruit!) in a cat’s diet can cause digestive or diabetic issues over time. It’s ultimately recommended to not feed cats apples in large quantities, especially as a meal replacement.
If you do feed a cat a part of your apple, that’s OK but be sure they don’t eat the seeds. The apple itself is non-toxic for cats, but the seeds contain are poisonous for cats.