[MacCatalyst] OperatingSystem is currently not working

[PureWeen]

Description

It looks like on MacCatalyst the Build on the Environment.OSVersion.Version is set to "-1" so when you call

if (OperatingSystem.IsMacCatalystVersionAtLeast(18,0))

it resolves to false.
This works fine on iOS just not MacCatalyst

Reproduction

aoperatingsystem.zip

Just run the app and I've set a label on the screen to output the value of OSVersion.Version. I've also included some if statements in the main page you can break point

Catalyst

iOS

[drasticactions]

TL;DR macOS reports 18.0, SDK parses it as a Version which is where the -1 comes from, Runtime check will always report it as below.

https://github.com/drasticactions/MauiRepoRedux/tree/MacCatalystVersion

https://github.com/dotnet/runtime/blob/abde3f9498f09b5016a7a0d7d2e1b81ce5c1b614/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs#L227

https://github.com/dotnet/runtime/blob/abde3f9498f09b5016a7a0d7d2e1b81ce5c1b614/src/libraries/Common/src/Interop/OSX/System.Native/Interop.iOSSupportVersion.cs#L11

https://github.com/dotnet/runtime/blob/abde3f9498f09b5016a7a0d7d2e1b81ce5c1b614/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs#L328-L341

xamarin-macios/src/ObjCRuntime/Runtime.cs

Lines 2688 to 2702 in 0db186c

	#if __MACCATALYST__
	static string? _iOSSupportVersion;
	internal static string iOSSupportVersion {
	get {
	if (_iOSSupportVersion is null) {
	// This is how Apple does it: https://github.com/llvm/llvm-project/blob/62ec4ac90738a5f2d209ed28c822223e58aaaeb7/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm#L100-L105
	using var dict = NSMutableDictionary.FromFile ("/System/Library/CoreServices/SystemVersion.plist");
	using var str = (NSString) "iOSSupportVersion";
	using var obj = dict.ObjectForKey (str);
	_iOSSupportVersion = obj.ToString ();
	}
	return _iOSSupportVersion;
	}
	}
	#endif

xamarin-macios/tests/common/PlatformInfo.cs

Line 82 in 0db186c

platformInfo.Version = Version.Parse (version);

That value is coming from SystemVersion.plist, which is 18.0, hence why it would get -1, since it's Version.Parseed and it doesn't have the Build number that it may have had in the past.

https://github.com/dotnet/runtime/blob/abde3f9498f09b5016a7a0d7d2e1b81ce5c1b614/src/libraries/System.Private.CoreLib/src/System/OperatingSystem.cs#L344

It may be that this needed that the -1 check needs to also be added to build for the same reason as revision, since it can't be assumed that build will be there. Or the SDK code above that fetches the version should always include the build even if the system doesn't provide it.

To work around it, checking against18 0 -1 should work

[rolfbjarne]

This issue was moved to dotnet/runtime#108694