Xcode 11.0 GM Seed 1 was released on 10 Sep 2019 and requires macOS 10.14.4+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_11_GM_Seed/Xcode_11_GM_Seed.xip.
Release notes are located at https://developer.apple.com/documentation/xcode_release_notes/xcode_11_release_notes.
The SDKs it contains are:
- iOS 13.0 (Build 17A566)
- macOS 10.15 (Build 19A547)
- tvOS 13.0 (Build 17J559)
- watchOS 6.0 (Build 17R566)
The compilers it contains are:
- clang 11.0.0 (Build 1100.0.33.8)
- swift 5.1 (Build 1100.0.270.13)