This is exactly what patents are supposed to protect you from. If you have a good idea, then file a patent and protect yourself. If it’s worth $500k per year then it’s worth having a patent lawyer help you do it right. Get the core stuff patented, not just the fluff. This way Apple can’t just pull your livelihood from you.
If you tried to patent your idea and it wasn’t patentable, then it’s probably not really your idea, and you can’t feel bad when Apple steals something that isn’t yours.
But you have to do this sooner rather than later. If you wait until your app has become a feature in iOS then it’s too late.
Want proof that patents are necessary? Just look at how many patents that Apple, Samsung, SpaceX, etc. have.