Smartphones do a heck of a lot these days. They are like mini-computers. That said, they store a lot of information, and are loaded with stuff that you may not want others to obtain: photos, personal information, contact info, location info, etc.
That’s why you have to protect yourself, and your iPhone from these sorts of things. Ars Technica put together a guide that’s designed to help iPhone owners protect themselves from stalkers or nosy friends.
It’s especially a problem after a breakup or separation of some kind. If you were the main account holder for your Apple ID and managed all those devices, it can be easy for that other person to start using your Apple ID to make purchases of to mess with your stuff. Ars refers to a story posted on Reddit about a dude who changed contact info on his girlfriend’s iPhone to see who she was talking to and so that he would receive messages instead of the friends she thought she was sending it to. He later realized that was he did was a douchebag move and felt guilty, but that just goes to show how easy it is to invade someone’s privacy.
Check out their full guide here.