I've just started experimenting with a macOS / iOS app combo called Kanbanier, which is a rather nice interpretation of the kanban concept. It uses iCloud to sync between platforms, and this works pretty well. But if you invest in the Pro version on the desktop (which gives you multiple swim lanes and a couple of other useful features), you'll find you also have to invest in the Pro version on iOS, otherwise you are suddenly told that your files are incompatible.

It's nowhere near as sophisticated as e.g. Trello, or not yet, but it's clearly a work in process and offers colours and tags. The tags are currently not used for anything, but presumably there's a Cunning Plan that's going somewhere.

I rather like it!

a macOS / iOS app combo called Kanbanier,

??

this?

https://kanbanery.com

Nope, this:

http://www.kanbanier.com

Got it (and got, it).

Well, glad that it was free. Has no visible means of copying and exporting data to OPML, text, or otherwise. Or importing. It's pretty, but also an island app.

I'd suggest Curio's "stacks" figures make much better Kanban-ical figures.

Absolutely agree about Curio, but there's no way it's ever going to make it over to iOS.

And Kanbanier, while "closed", is still in development and works very well between Mac and iOS devices.