Xcode 10.2 Beta 3 was released on 19 Feb 2019 and requires macOS 10.14+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_10.2_Beta_3/Xcode_10.2_Beta_3.xip.
Release notes are located at https://developer.apple.com/documentation/xcode_release_notes/xcode_10_2_beta_3_release_notes.
The SDKs it contains are:
- iOS 12.2 (Build 16E5201d)
- macOS 10.14.4 (Build 18E194d)
- tvOS 12.2 (Build 16L5201d)
- watchOS 5.2 (Build 16T5201c)
The compilers it contains are:
- clang 10.0.1 (Build 1001.0.43.3)
- swift 5.0 (Build 1001.0.63.8)