Can we use SwiftUI in Playground ?

I was just about to ask the same question! I assume we can, but I would wait for Apple to respond.

I hope we can because that's what I've been working with.

Sure! Why not.

It's an Apple framework, so I don't see any problem 😉

Of course You CAN

I am using UKIT, to write my playground. You can even use external framworks. However, you should include them in your .zip file and that .zip file should not be more than 25 mb.