User Profile

Hi. I just upgraded to Xcode 10.3. I've missed several upgrades, and haven't been using it. I loaded in a program I wrote and got the message my code uses Swift 3.0 and won't work in Xcode 10.3. And I need to load it into Xcode 10.1 to migrate from Swift 3 to Swift 4. So.How do I downgrade from Xcode 10.3 to 10.1? And -- is there a way to do it to preserve 10.3, so I don't have to re-install it again?Thanks.--PDN