Although Android as an operating system is much larger than iOS, Apple is dominating if you pick the numbers of individual devices apart. This is evidenced by a report by researchers at Counterpoint.
The report was written in October, which means that Iphone X is not included. Among other things, it was good for Iphone 8 and Iphone 8 Plus that the models sold almost twice as much as the nearest competitor Samsung Galazy S8 Plus and Galaxy Note 8.
But it does not end there. Even Iphone 6, which is now three years old, sold better than the Galaxy S8.
Furthermore, Counterpoint writes that Apple is the largest in the $ 400 and up price segment. On the other hand, they have not managed to get hold of the middle segment and are seen by Chinese manufacturers like Vivo and Oppo.