Given the fact that currently Xcode 9 is beta and the main interest today is getting knowledge of iOS 11 the question is admittedly odd...
Is there a way to target iOS 10 as base sdk while working in Xcode 9 beta? Is there need for Apple to package the SDK for Xcode 9 the same way they do for previous OS's in Xc8?
Why would one want this?
a) The first thing that comes to mind is to use Xcode 9 nice new refactoring tools on a project that involves code that needs changes from iOS 10 to 11, but has currently to run on iOS 10.
b) the sake of experimenting..