Xcode 8 beta 3 requires macOS Sierra beta 3 or higher, or OS X El Capitan 10.11.5. Xcode 8 beta 3 includes SDKs for iOS 10.0, watchOS 3.0, macOS version 10.12, and tvOS 10.0. To develop apps targeting prior OS versions, see “About SDKs and the Simulator” in What's New in Xcode, available on developer.apple.com or, select Help > What's New in Xcode when running Xcode.
Xcode 8 beta 3 can coexist with previous versions of Xcode. (Note - running multiple instances of Xcode simultaneously is not supported.)
Developers can download Xcode 8 beta 3 from the link below...