Xcode 10.0 Beta 6 was released on 13 Aug 2018 and requires macOS 10.13.4+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_10_Beta_6/Xcode_10_Beta_6.xip.
Release notes are located at https://download.developer.apple.com/Developer_Tools/Xcode_10_Beta_6/Xcode_10_Beta_6_Release_Notes.pdf.
The SDKs it contains are:
- iOS 12.0 (Build 16A5354b)
- macOS 10.14 (Build 18A361a)
- tvOS 12.0 (Build 16J5349a)
- watchOS 5.0 (Build 16R5349a)
The compilers it contains are:
- clang 10.0.0 (Build 1000.10.43.1)
- swift 4.2 (Build 1000.0.36)