I recently wrote a small side project using vala + gtk4.
I tried blueprint, and while I liked the format, I struggled with a lack of documentation on how to do some more advanced things. Gtk's .ui files are ok, but you still end up writing a lot of code to hook everything up.
While I really like vala as a language, I think it'd be great to write all my logic and models in vala, then use this swift library for the UI.
In the context of Gnome/GTK development, there's almost nothing more stable and comprehensive than Vala, as it's been around a very long time and was created specifically to occupy that space. Can't speak for OP about why to combine it with Swift handling the UI, but certainly Vala still has far better support for the Gnome data model and APIs outside of those specific to the GUI.
I get that, but if you're going to deal with the impedance mismatch anyway, I would just go all in and use Swift for everything. But I guess that's assuming that GTK/GLib is fairly easy to wrap in a language like Swift, which I assume is true given all the different language bindings out there.
I think a difference between Vala and everything else is that Vala has been written with gobject as its "native" object system whereas everything else uses the glib bindings.
Kinda like using COM from Visual Basic 6 vs using it from plain C.
I tried blueprint, and while I liked the format, I struggled with a lack of documentation on how to do some more advanced things. Gtk's .ui files are ok, but you still end up writing a lot of code to hook everything up.
While I really like vala as a language, I think it'd be great to write all my logic and models in vala, then use this swift library for the UI.