Xcode 6.0.1 Release was released on 17 Sep 2014 and requires macOS 10.9.4+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/xcode_6.0.1/xcode_6.0.1.dmg.
Release notes are located at https://developer.apple.com/library/content/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW450.
The SDKs it contains are:
- iOS 12A365
- macOS 13F26
The compilers it contains are:
- clang 6.0 (Build 600.0.51)
- swift 1.0 (Build 600.0.51.4)
- LLVM-GCC 3.5 (Build )