Create a Professional iOS App in Hours with Creo
medium.com
medium.com
> Read it again: entirely rewrite a core component created by some of the smartest programmers in the world, with no access to their source code.
They didn't though. Looking through their documentation[1], they subclassed all (or some?) UIKit components and offer those instead of what UIKit offers – which is what allows them to hook into each object's properties for their IDE (I'd guess).
It's cool, and I understand why they did this given their offering (a drag-and-drop IDE to create apps) – but they definitely didn't rewrite a massive, complex, UI framework. Similarly, they blocked off a bunch of UIKit stuff that could genuinely be useful. It looks like you can't provide your own collection view layouts, for example.
We are able to execute most of the native iOS code directly on Mac, from example this project works without a single code change on MacOS: https://github.com/chrismiles/CMUnistrokeGestureRecognizer (so we have UIView, UIViewController, UIGestureRecognizer, UITouch, UIBezierPath and much much more).
We also didn't block any customisations (like the custom collection view layouts). We simply need more time in order to correctly expose all the functionalities from a graphical user interface and in a coherent way for all the users.