Swift 3 - dynamic vs @objc

Question

What\'s the difference between marking a method as @objc vs dynamic, when would you do one vs the other?

Below is Apple\'s definition for dynamic.

Answer 1

As that quote says, dynamic implies @objc.

Unless you specify a class as being dynamic, the compiler is free to optimize away and inline its methods. This brings huge performance benefits, but it means that you can't change those method implementations at run time. If you're planning to mess around with those methods at runtime using the reflection capabilities of the Objective C runtime, you'll need to use dynamic. You'll incur a performance penalty (your code will run at Objective C levels of speed, rather than near C-like levels), but you'll gain that extra dynamism.