 <p>It should be as easy as adding the file to your extension target/project so that both are part of the same module. Same module means internal scope and the constant should be accessible from the other file automatically.</p> <p><a href="https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/AccessControl.html" rel="nofollow">https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/AccessControl.html</a></p>