How do I install Xcode 9 without updating macOS?

Question

Does anyone have any idea to install Xcode 8 OR Xcode 9 without updating macOS?

I want to update my Xcode 7.1 to Xcode 8 or Xcode 9 (or 9.1) Beta.

But it is

Answer 1

I have two Apps in the Mac App Store. My main development machine is still running OS X Yosemite. One App started showing some small GUI problems when used on MacOS Sierra. So I installed XCode 8 on my MacBook Pro, running MacOS Sierra. Next, I migrated the code to Swift 2.3 (3.0 was too much of a hassle for now), and archived and exported the App (without changing any build-settings). The GUI problems (mostly related to resizing images and windows) are solved now in the App, when run with MacOS Sierra. And the App still works with OS X Yosemite and OS X El Capitan.

Perhaps it depends on the settings you use in XCode 8, but Apps compiled/built with XCode 8 should definitely still work with OS X Yosemite and El Capitan.. Unless you use specific features/functions of the MacOS Sierra SDK, of course.