Don't usually associate iOS with fragmentation, but makes sense when it comes to screen sizes I guess - esp w the iPad pro now

Fragmentation is also increased with apple's recent obsession with breaking iOS and/or changing how fundamental APIs work.

Are you sure thats recent? Its been like that ever since I started programming for the iOS platform (3 years ago) and before its something you would hear about pretty consistently with each major iOS update.

I feel like it got much worse when iOS 7 launched.

I personally don't equate fragmentation with different screen resolutions/sizes/aspect ratios. An eco system should have a large swathe of options. One size does not fit all in this case.

The fragmentation I feel in iOS comes from its tedious way to deal with the different screen types.

iOS's adaptive display lumps displays into four different categories. A category can have vastly different screen sizes and even different aspect ratios. They are...

iPad Pro, iPad (portrait, landscape)

iPhone 6 Plus (landscape)

iPhone 6, 5, 4S (landscape)

iPhone 6 Plus, 6, 5, 4S (portrait)

AutoLayout is suppose to fill in the gaps between the different resolutions here, but it doesn't do that great of a job at it. It relies heavily on hardcoded values rather than dynamic values based on the containers size. That coupled with only having 4 distinct size classes makes laying out most views near impossible to rely on AutoLayout alone, you have to manually change the constraints at runtime.

I don't find iOS's layout system to be very adaptive at all. The only thing saving it is there are only 6 different resolutions in the entire eco system. With a huge majority of the users on only one or two of those resolutions.

Jesus, iPhone app development is pretty much as terrible as I always imagined. Not in the actual development itself, but in convention and mindset.