I am attempting to bring a Swift 3.x application up to date to the latest version of Swift by executing conversions in old versions of Xcode. This has brought me to Xcode 9.x.x. So, I attempted to install Xcode 9.x.x on a 16-inch MacBook Pro running Catalina 10.15.2. I tried both 9.4.1 and 9.3.1. Both failed with error:
Dyld Error Message: Symbol not found: _OBJC_IVAR_$_NSFont._fFlags Referenced from: /Applications/Xcode 9.4.1.app/Contents/MacOS/../SharedFrameworks/DVTKit.framework/Versions/A/DVTKit Expected in: /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit in /Applications/Xcode 9.4.1.app/Contents/MacOS/../SharedFrameworks/DVTKit.framework/Versions/A/DVTKit
I suppose AppKit in 10.15.2 no longer possesses the symbol expected by Xcode. Am I correct to conclude Xcode 9.x.x is not supported on Catalina?
If this is the case, how can I obtain a copy of High Sierra or Mojave to run Xcode from there? I understand I may not be able to run these operating systems natively on the 16-inch MacBook. Is it possible to run these older OS versions in a VM?
And if you want to use an older macOS, you'll need to find it in your purchase history via the MAS.
No comment on VM.
See your other similar thread: What is the recommended way to upgrade Swift 3.x apps on Catalina?
Xcode 10.0 seems to allow the migration by the way.