Comment by developer2

Aha, what I was looking for was the "Library" popup, which allows drag-and-drop of new components onto the canvas. Now I understand; this latest iteration of Xcode has the code <-> canvas being bidirectional, so using the library or canvas inspector just edits your code anyway! Interesting. I'll have to run through some docs and tutorials to see if I can finally pick up macOS/iOS app development.