How to find out which version of Swift is installed on my Mac and in Xcode?

Hi everyone! I'm a beginner iOS developer and I'm confused about Swift versions. I installed the latest version of Xcode, but I often see code examples online that only work on a specific version of Swift. For example, I'm trying to use `#warning` for TODO markers, but Xcode complains: ```swift #warning("Finish implementing the authorization logic") // Error: 'warning' is only available in Swift 4.2 or newer ``` I don't understand which version of Swift I'm using. In the terminal, I type `swift --version`, but it shows some number like "5.10", and in Xcode settings it says "Swift 5" — is that the same thing? Also, if I open an old project written in Swift 3, will it work on my version of Swift? Please explain how to accurately determine the version of Swift used in my project.