Helllo, good question, and the answer is simple, I am more familiar with Objective-C and I get used to it.

Aren't you worried about Apple killing ObjC down the line?

Their whole UI is written in ObjC, they've got two decades of Mac apps in ObjC, and they wrote a whole new language to interface cleanly with ObjC but with nicer semantics, so I'm guessing ObjC isn't going anywhere.

But even if Apple does remove it, everything apart from the UI would still compile in GCC's ObjC compiler. The guts of this project is the PDF engine, not the UI, and that would still work. TeX is written in a language that pretty much only Knuth uses, and it's still very much working.

More than just their UI, fundamental parts of Apple's OSes are written in ObjC, including very new components like ARKit, CoreML, and the Metal API. Apple continues to write tons of new Objective-C code every day. Of course Swift is making inroads inside Apple, but Objective-C has to be well supported for a very long time to come.

I've been writing Objective-C for 15 years, and continue to do about 60-70% of my work in ObjC (the rest is mostly Swift). I'm not particularly worried about my code being unusable anytime soon. When Apple starts making a real effort to wholesale migrate away from ObjC, I will too.

What about Cocoa? You think it still makes sense to invest dev time in a Cocoa app?

That's a little more ambiguous. Until very recently I was primarily a Cocoa developer (took a full time iOS dev job a few months ago), and it still makes up a significant portion of my side work, so I'm biased. But right now, the alternatives are SwiftUI and UIKit/Catalyst. SwiftUI nicely integrates with AppKit/Cocoa, but anyway, it's in pretty rough shape on the Mac at the moment (see https://news.ycombinator.com/item?id=24472063 for example). Catalyst is (IMO) basically garbage if your goal is to make a great Mac app. Its purpose is to allow easy porting from iOS to Mac, not to create truly good Mac apps.

Obviously, the presence of these two technologies, and Apple's pushing them is evidence that Cocoa may be on its way out, but it's not deprecated, and is still officially the recommended way to build true Mac apps. Undoubtedly it's SwiftUI (not Catalyst) that will eventually displace it, but especially on the Mac, SwiftUI is not really ready for production yet.

I agree with all your points.

I considered getting into Cocoa dev but between the lack of resources and the probability that Apple will kill it in the not so distant future, it didn't make much sense.

Better wait a couple of years until the mud settles.

I think that's eminently reasonable. As someone with 15 years experience doing Cocoa dev, the intention to be a Mac dev indefinitely, and hundreds of thousands of lines of existing Cocoa and Cocoa Touch code, it's just going to be a slow transition. But there's no pressing reason to just stop writing any new Cocoa code (I literally wrote some since my last comment :-P). If I were starting now, I'd probably focus on SwiftUI with the assumption that it will be the way to start most new projects within the next few years.

Aside: is there any way to demo PDFScanner? I literally got a Epson FF680W today and was shocked at how poor the default software is for reading documents. I tried VueScan (which everyone recommends online) but found the interface awful.

Aaah, trial versions on the App Store :( I'm still not sure what would be the best way to implement a demo version for an App Store only app - I loathe the "Free with IAP" model. If you want to test if your scanner works with PDFScanner, try to use it with the Image Capture application that comes with macOS. It uses the same library as PDFScanner to talk to the scanner, so if your scanner works there, it will also work in PDFScanner.

I am a happy user of PDFScanner. How are you doing the OCR?

I use the hocr feature of tesseract and parse the resulting xml that contains all the text with bounding boxes.