After reading the Apple Developer document (Apple Developer Docs), I found that:
"The Xcode debugger includes an interactive version of the Swift language called REPL (read-eval-print-loop) ... can be accessed through the Xcode console or terminal.
Unfortunately, it doesn't tell you how to access from the terminal. Fortunately, this is not a difficult thing.
Enter the following command (whichever beta you use to change the app's name)
Copy Code code as follows:
Alias swift= "/applications/xcode6-beta2.app/contents/developer/toolchains/xcodedefault.x
In the terminal window, you see the following information. Enter Swift now and you will see the Welcome page.
Note: When a new beta is present, you need to update your alias, enter the same command, different app names. For example, Xcode6-beta3.app.
Now you can see your swift code:
Finally, if you type: Help, then the LLDB debugging commands are handy.
Why don't you load Swift playground?
This is a good question. I personally appreciate the ability to program without a syntax error without starting Xcode 6 beta and opening a swift playground. Again, I am sure to comply with NDA, I will not post a screenshot of Xcode 6 until it is finally released.