That's why I wish there was an official API to take the split view version of the app that the developer already created, and use that to relatively easily create a same-app split view.
I don't think it's as simple as that. The Split View version is still just a single view of an app at a time. Apps would have to be updated to handle multiple views.
I can see two ways to approach this:
- Run a separate instance of an app for each view. This would probably be a waste of resources, and the app would have to be aware that there are other instances, or it's just gonna be a mess. I don't think this is a practical solution as it'd still require work by the developer to function properly.
- Run a single instance of an app that can handle multiple views/windows. This is probably what'd end up happening since it's basically the same paradigm as an app handling multiple windows on a desktop OS. Apple can provide frameworks to make this easier, but an app would still need to be updated to do so, and handle things such as moving open documents from one view to another of the same app.
Neither of these will just work out of the box with the way apps are created right now.
So now third party apps that support split view are going to need to support saving of multiple states, because they may be in multiple spaces?
No, that's just speculation on what I think is a natural step forward based on the changes they've made to the way Split View works. At the moment, it's still pretty much the same basic system in place as before, just with some usability improvements. The only major change in iOS 11 is that Swipe-over is gone and replaced by a floating app.