What about documented APIs that are flawed? I'm not an iOS programmer but let's imagine an API that requires an SHA-1 signature ... so those become insecure and the API is dropped - or an API that offers an SSLv1 connection and that's insecure so it gets dropped. The only way to emulate that would be to re-introduce the problem.

Perhaps these are bad examples and the real reasons for Apple to not support something is not so neat - I don't know about them - but FWIW my experience from working at Nokia was that compatibility was a big drag to being able to implement improvements and it's a huge effort to maintain it that doesn't come for free.

I see what you're saying - that we can't run old iOS apps on our phones because some features / APIs have been removed. And there are some APIs which have been taken out, and Apple has forced developers using them to update their apps.

The two most ready examples of this sort of thing are that (I think) 32 bit apps aren't supported any more, and that the HID guidelines specified the fixed pixel dimensions that iphones were. That isn't something you can assume any more.

But if I want to run an ancient version of flappy bird, I don't really need it to run on my modern iphone - just like I don't need modern windows to support 1991 QBASIC in order to run my old qbasic programs from when I was a kid. We need two things:

- Access to old versions of iOS app binaries. I have no idea how to get these, if they're available anywhere in the app store (or can be backed up), or if apple deletes them.

- Access to an early iOS simulator / emulator to run those apps on. Apple has had fantastic iOS simulators going all the way back to the first app store releases, though I think they only ran ios apps compiled to x86.

It'd be great if there was a way to run old ios games and apps and things. I don't want those heady days of early ios apps to be lost to history.