I have a program that was written In Swift 3 a few years ago and haven't updated it for quite a while. I am now using Xcode version 11.2 and when I load this program into Xcode it tells me to use Xcode version 10.1 and migrate the Swift 3 code into Swift 4 code. I have made several attempts to create Xcode version 10.1 but all have failed for one reason or another.I downloaded the file Xcode_10.1.xip from Apple Developer but when I tried to unzip the file a message told me that the file was not from Apple and wouldn't unip it.In another attempt I found an old Xcode_10.1 version in Time Machine and restored it to a copy of Xcode. When I tried to run it a message said that I needed to load some new components into it but when I did that it quit with an unknown error.If I can't migrate my program from Swift 3 to Swift 4 my program is toast. Can anyone help me?FredErixon