Using an iPhone nowadays is hard work in trying to remember all the swipes, pokes and prods to do something straightforward. Not only is a book of instructions needed but that book needs to be carried with the iPhone - always. Just as soon as you get the hang of something, Apple decides to do an ‘improvement’.
Once I was a purveyor of any new iPhone/iPad app, but now I cant be bothered - would just add more unnecessary complications.
My hope is that Apple never loses control of its App Store otherwise things will get much more messy.