Ase per Testing iOS Application on MacOS the most recent version of Xcode available is 10.2 (10P99q), which is the beta 3 build. The 10.2 GM was released on March 25th. I think is is fair to expect support for the most recent versions of the IDE fairly quickly after their public releases.
@alexey could you please provide some insight in the Xcode 10.2 roadmap?