You don't use Xcode to write Swift, you use Xcode to write Apple apps which you happen to do in Swift. No matter the language, you need Xcode to write those app

You don't use Xcode to write Swift, you use Xcode to write Apple apps which you happen to do in Swift. No matter the language, you need Xcode to write those apps. Equalling Xcode and Cargo makes no sense. A similar situation to Xcode and Swift would be like Visual Studio and C# on Windows. Many developers use these tools, but they are not the language ecosystem, and the Cargo equivalents are entirely separate (Nuget, Cocoapods).