Xcode 9.4 Beta 2 was released on 1 May 2018 and requires macOS 10.13.2+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_9.4_beta_2/Xcode_9.4_beta_2.xip.
Release notes are located at https://download.developer.apple.com/Developer_Tools/Xcode_9.4_beta_2/Release_Notes_for_Xcode_9.4_beta_2.pdf.
The SDKs it contains are:
- iOS 11.4 (Build 15F5061c)
- macOS 10.13.4 (Build 17E189)
- tvOS 11.4 (Build 15L5560b)
- watchOS 4.3 (Build 15T212)
The compilers it contains are:
- clang 9.1.0 (Build 902.0.39.2)
- swift 4.1.1 (Build 902.0.53)