[martin-adams]

It's because they've recreated the internal menus, window snapping, ability to overlay windows and has a desktop. It looks like an OS. Apple were against this in the past because it doesn't align with their OS way of doing things. I never liked the rule so I'm excited to see that it looks like they've relaxed it in recent years.

[egwynn]

I don’t think they’ve ever had a policy about whether apps could / couldn’t re-create their own menus or windows.

[martin-adams]

I finally found it. It's the "create an alternate desktop environment" part that I would say this falls under. Mostly because you have a desktop and they've created a new windowing environment that isn't native to iOS.

>> 2.5.8 Apps that create alternate desktop/home screen environments or simulate multi-app widget experiences will be rejected.

https://developer.apple.com/app-store/review/guidelines/

[egwynn]

Got it. Yeah I see what you mean. This rule is more about them wanting to maintain control over distribution than it is about having a custom desktop / windowing metaphor. They don’t want people to create a platform within their platform where a third-party is distributing app-like things in an end-run around the iOS App Store.