I download Xcode 9 beta and run the XIP file on Sierra 10.12, but always get the "file is corrupted" message. What can I do about it?
May be a Xip issue.
Solution proposed : Right-click on the downloaded .xip file and pick Open With > Archive Utility
Look at this : h ttps://forums.developer.apple.com/thread/80540
Which version of OSX exactly ?
XCode 9 beta 5 requires 10.12.4 at least.
Did you try to download from another broser (Chrome vs Safari for instance). It seems in the past that Safari corrupted files.