Hello!
In our codebase we have a NSView subclass that conforms to NSTextInputClient. This protocol is currently not marked as a main actor, but in the decade this has been in use here it has always been called on the main thread from AppKit.
With Swift 6 (or complete concurrency checking in Swift 5) this conformance causes issues since NSView is a main actor but not this protocol. I've tried a few of the usual fixes (MainActor.assumeIsolated or prefixing the protocol conformance with @preconcurrency) but they were not able to resolve all warnings.
So I dug in the AppKit headers and found that NSTextInputClient is usually implemented by the view itself, but that that is not a hard requirement (see NSTextInputContext.h the documentation for the client property or here). With that I turned my NSView subclass extension into a separate class that is not a main actor and in my NSView subclass create an instance of it and NSTextInputContext. This all seems to work fine in my initial tests, the delegate methods are called. But when the window loses and then regains key, I see a warning message in the console output.
-[TUINSCursorUIController activate:]: Foo.TextInputClient isn't subclass of NSView.
So my question is, am I doing it wrong with the custom class that implements the protocol? Or is the warning wrong?
I would also appreciate a hint on how to better resolve the concurrency issues with NSTextInputClient. Is a main actor annotation coming at some point from your end?
Thanks!
Markus