[Nullability] NSView.Window & SuperView should be allowed to be null

[snechaev]

https://github.com/xamarin/xamarin-macios/blob/9ea3cff36c86b1c3c46fb0872543165046b507a8/src/appkit.cs#L16088-L16097

The current implementation of the NSView.Window marked as non-nullable. But the Apple docs states that:

The value of this property is nil if the view is not currently installed in a window.

The same thing with a NSView.SuperView - the docs:

The value of this property is nil when the view is not installed in a view hierarchy.

[tipa]

This change would finally resolve the false-positive warnings I get in Rider (at least partly): https://youtrack.jetbrains.com/issue/RSRP-494672

I believe the launchOptions parameter for application:didFinishLaunchingWithOptions: should also be annotated as nullable. Plus there's a whole lot more here or here. If it's just a missing annotation that could resolve it, like in the linked PR, it shouldn't be too difficult to resolve all these. Would have certainly prevented some crashes in my case :)

[snechaev]

I believe the launchOptions parameter for application:didFinishLaunchingWithOptions: should also be annotated as nullable.

I don't see this declaration anywhere except in the templates
https://github.com/xamarin/xamarin-macios/blob/9ea3cff36c86b1c3c46fb0872543165046b507a8/dotnet/Templates/Microsoft.iOS.Templates/ios-tabbed/AppDelegate.cs#L10-L11

So it looks like this can be manually annotated when creating the project (the template should be fixed to avoid manual fixes in the future). @tipa, am I missing some use case (I have no experience with iOS)?

[snechaev]

by the way, the #21599 will only fix this for macos, not ios. I can add commits in the existing PR or create the new one.

https://github.com/xamarin/xamarin-macios/blob/9ea3cff36c86b1c3c46fb0872543165046b507a8/src/uikit.cs#L16921-L16929

[rolfbjarne]

by the way, the #21599 will only fix this for macos, not ios. I can add commits in the existing PR or create the new one.

9ea3cff/src/uikit.cs#L16921-L16929

I've created a PR for iOS as well.