Q:

what is "cin" (in C++) command in Swift? 

What is the equivalent of statment cin >> x (in C++), in Swift which asks the user to input some values from keyboard.  How can I achieve this in Swift-language? 

A:

Swift is not C++ or anything else.  To print out a message in this language you can start with:

println("Hello, world")

And to get user input you can use objective-C ways:
let stdInput = NSFileHandle.fileHandleWithStandardInput()
let usrInput = stdInput.availableData

