The Foundation stuff is a complete Swift re-implementation of Foundation (fairly impressive goal) and is still in-progress (basic classes like NSArray and NSData look complete but none of NSURLConnection is implemented). They are targeting Swift 3 to have them complete. As the Core Libraries project page says:<p>&quot;These libraries are part of the work towards the future Swift 3 release. They are not yet ready for production use, and in fact are still in the earliest stages of development&quot;