Playground (a.k.a REPL) is one of the most useful tools for understanding a programming language. Swift provides a very easy to use playground that makes it very easy for us to try out Swift code and see the results.
If you look at other programming languages, most of the modern languages have some kind of playground mechanism. In addition, there are many languages that provide a web playground.
The web playground gives us many more power. It can be used to try out an idea on your smartphone, to share problematic code and execution results with others for discussion, or to provide "working documentation" where you can run sample code for documentation.
Unfortunately, the official Swift web playground is not yet available, but you can use server-side Swift and web technologies to create your own web-powered Swift Playground!
Here is Swift web playground I created and host => https://swiftfiddle.com/ .
I usually work in iOS and macOS programming, so the experience with server-side Swift and web programming are very interesting to me. I'd like to see more community-based Swift execution environments like this one, so I'd like to share the insights I've gained from building this playground, such as how to sandboxing execution, limit resources and switch Swift versions etc.