It's pretty insane for a programming language to be on version 4 already. Even a recently invented language like PHP, which is 20 years old this month, is only on version 4. (It really started on version 3, skipped version 6, and is now on 7 -- but it's really 4.) Python is nearly 30 years old, is hugely popular, and it's still on version 3. Objective-C, Swift's precursor, is 34 years old and is still on version 2. They're all great languages, which is why they're still being used. Why is Swift changed so frequently? Anyone guess?