Xcode 10.2 Beta 4 was released on 4 Mar 2019 and requires macOS 10.14.3+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_10.2_beta_4/Xcode_10.2_beta_4.xip.
Release notes are located at https://developer.apple.com/documentation/xcode_release_notes/xcode_10_2_beta_4_release_notes.
The SDKs it contains are:
- iOS 12.2 (Build 16E5212e)
- macOS 10.14.4 (Build 18E205d)
- tvOS 12.2 (Build 16L5212d)
- watchOS 5.2 (Build 16T5212d)
The compilers it contains are:
- clang 10.0.1 (Build 1001.0.46.2)
- swift 5.0 (Build 1001.0.69)