ios - How can I programmatically find Swift's version?

Question

I know I can find the version of Swift I'm running right now reverting to a Terminal and typing:

xcrun swift --version
Swift version 1.1 (swift-600.0.57.4)
Target: x86_64-apple-darwin13.4.0

Also, I've been reading about the Preprocessor Macros in Swift, but no luck finding a Swift version constant.

As Swift 1.2 approaches it will be nice to flag old code that only runs on Swift 1.1 (Xcode up to 6.2) or new code that needs Xcode 6.3 (Swift 1.2)

Note: I can also use system() to do something like:

system("xcrun swift --version | grep version > somefile.txt")

Then open somefile.txt, but rather prefer some simpler solution

Answer 1

You can use conditional compilation directives to test for the specific Swift version used to build your project:

#if swift(>=5.0)
print("Hello, Swift 5!")
#elseif swift(>=4.0)
print("Hello, Swift 4!")
#elseif swift(>=3.0)
print("Hello, Swift 3!")
#elseif swift(>=2.2)
print("Hello, Swift 2.2!")
#elseif swift(>=2.1)
print("Hello, Swift 2.1!")
#endif