I too was reminded why they call this macOS Beta. The progress bar would complete, then start again and end at about 5%, not moving even after several hours. I could log in in Safe Mode, but the Finder would lock up almost immediately. I just gave up, erased the entire drive, and reinstalled, thankful for iCloud Drive and Dropbox (eh, except the Dropbox app isn't compatible with Big Sur 🙁)

I figured it out, I needed an entry in Info.plist.

Yes ... and no :-( What I want is to a) create a folder, CrosswordRewind, inside the sandbox's Documents folder, and b) put up a gorgeous UI to show me that folders contents (with UIDocumentsPickerViewController). I've accomplished a), and the reason I said "yes ... and no" is because I can see CrosswordRewind on the simulator, not on an iPad The folder got created on the iPad (I can see it thanks to the Devices window), but Files is showing me 3 folders -- Minecraft, Exploring EDU, and Recovered Files. I have 3 theories: I'm using the wrong class. The docs say a UIDocumentPickerViewController is a "view controller that provides access to documents or destinations outside [my emphasis] your app's sandbox." They don't say anything about inside. I've misconfigured UIDocumentPickerViewController somehow, so it won't show me (on the iPad) my current Document folder. What I'm saving isn't actually a UIDocument -- maybe that's illegal (but just on the iPad)

cookieapps, thank you so much! All I had to do was fiddle with the scroll bars, and I'm sure that I would've figured that out ... sometimes in the early 2030's 😀

Thanks for your reply, KMT, that inspired me -- I created a new project in Xcode 12 beta, and got the same error, so it's not just my current app. It must be something on my end, otherwise I'm sure more people would have run into this, but I filed feedback anyways: it shouldn't happen on any system.

Update: reinstalled Xcode beta, that didn't help either. And, for once, I actually read the release notes, and did not see this mentioned.

Thanks, thegathering - I bow to your superior Googling skills 😀

I have this same problem, I'm sure Apple's going to get right on it.

The solution is, when becoming first responder, to set the UITextField's selectedTextRange to nil.

The documentation now states that this property is ignored in Mac Catalyst (I'm not sure if that was there when I originally posted the question).

Do you have a UITextFieldDelegate setup? It defines the appropriate methods, e.g., textFieldDidBeginEditing(), textFieldDidEndEditing(), etc.