I will take your one phone as disproving all of my experience. Thanks! In all seriousness, I have an iPhone 4S whose battery is in tatters but also hasn’t swol

I will take your one phone as disproving all of my experience. Thanks! In all seriousness, I have an iPhone 4S whose battery is in tatters but also hasn’t swollen (that I can tell, anyway). It doesn’t happen to every single battery. It does happen to a significant portion of them over time.