Maybe you can help me fill in the gaps as to how this is a monopoly. Now depending on where you go for a definition of a monopoly, you might find subtly different definitions. But to quote Investopedia:
> A monopoly is characterized by a single company supplying a good or service, a lack of competition within the market, and no similar substitutes for the product being sold.
Apple's iPhone is produced by a single company, you're right. But there is competition within the market thanks to Android, and other failed attempts at competition like Blackberry and the Windows phones.
Furthermore, Apple might "stop" other competition from springing up by virtue of just being a better offering, but I don't believe anyone is quite literally halting someone from attempting to start a competing phone OS and hardware business. If the only choices are Android vs iOS, and the slew of Android phone manufacturers vs Apple, should Apple be held accountable for nobody making better offerings than what already exists? In my opinion, that answer is only "yes" if you can prove they're doing anything in back alleys to cut prospective competitors off at the knees, which as far as I know, doesn't happen. Maybe you can point me to where and how they do, though.