Since Feedback Assistant is broken in Catalina beta 2, I'll drop this here.
Setup:
I'm about to release an AppKit app for Mac, but the vast majority of my code was written to be compatible with UIKit also (CoreGraphics, CoreText, AVFoundation, etc...), and since UIKit dev is so much easier, I'm beginning to convert my view/controller layer over to UIKitForMac.
Specifically, while migrating my NSDocument subclass to become a UIDocument subclass instead, and had to adjust a couple of overrides to be a little different...
I ran into an issue at run time where the log reported that +[MyTargetName.MyUIDocumentSubclassName readableTypes]: unrecognized selector sent to class 0x######### (4 times).
Of course, +readableTypes is an NSDocument class property, not a UIDocument method. So I searched my entire project for any readableTypes calls, and there were none. The stack trace indicated it may be the system machinery calling this on the document subclasses it got from my info.plist document type declarations, which I had copy/pasted from the old AppKit version of the app. (I haven't checked to see if those need to change, so maybe you're assuming it should be an NSDocument based on the layout of those entries? I dunno.). As I understand it, AppKit would call an unrecognized selector a few times hoping someone might add it... so I don't know if this is actually causing a problem I haven't found yet. Certainly, it made determining that or why the UIDocumentBrowserViewController isn't working in beta 2 harder to track down.
After I added a readableTypes method to my UIDocument subclass, I started getting another unrecognizer selector, something like _is_java_subclass? or I dunno, I'm back to running beta 1 now (so I can get stuff done) so I can't reproduce that.
I don't know if this also happened in the beta 1 of catalina, since I had not finished migrating my NSDocument subclass to become a UIDocument subclass before I upgraded my mac to beta 2.
