Xcode 10.1 Beta 2 was released on 2 Oct 2018 and requires macOS 10.13.6+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_10.1_Beta_2/Xcode_10.1_Beta_2.xip.
Release notes are located at https://developer.apple.com/documentation/xcode_release_notes/xcode_10_1_beta_2_release_notes.
The SDKs it contains are:
- iOS 12.1 (Build 16B5068g)
- macOS 10.14.1 (Build 18B50b)
- tvOS 12.1 (Build 16J5584c)
- watchOS 5.1 (Build 16R5568d)
The compilers it contains are:
- clang 10.0.0 (Build 1000.11.45.5)
- swift 4.2.1 (Build 1000.11.42)