Apples to Apples, Part II (opens in new tab)

It's worth noting that Swift Ints (and Arrays) aren't primitives; they're named types defined as structs in Swift code in the standard library, and have methods and can be extended like any other types in the library (see [1]). That's why the unoptimized case is slow, and why the author gets such a dramatic speedup from optimization-- the Swift optimizer (unlike the Objective C optimizer, which, thanks to ObjC's messaging system, has to keep method calls intact) can use techniques like method inlining to bring performance to a point close to that of a native int/plain C array.

Regardless, I'd still like to see a comparison with C++ (where method dispatch looks a lot like Swift and the optimizer should be able to do similar things) and plain C. Might have to try that this evening if I get bored.

1: https://developer.apple.com/library/prerelease/mac/documenta...

Yeah, not to mention that NSMutableArray is not necessarily an array in Objective-C, see: http://ridiculousfish.com/blog/posts/array.html . It really seems like this benchmark is comparing different framework approaches more than any "core language speed" (similar to comparing stl::vector sort of ints in Objective-C++ to NSMutableArray sort of NSNumbers)

Just looking at the "std lib sort", what this might actually be testing off the top of my head is:

1. C-style-array access/write speed of "native arrays" vs. potentially hash-mappy access/write speed of array-like NSMutableArrays.

2. Direct integer comparison (a < b) vs -[NSNumber compare:] method dispatch speed.

3. I don't know how sorted() is implemented internally in Swift, but given that no comparison method is being passed in, you may also be comparing a fast internal int[] sort that directly compares ints to the speed of calling the NSComparisonResult lambda O(n lg n) times.

Can anyone explain the reasoning behind this difference? The article only mentions "In Objective-C, NSArray and NSNumber are used intentionally as the counterparts to Swift's Array and Int."

Swift is slower in the debug mode and faster with full optimizations. I don't know either language, but I think NSArray cannot store primitive types, so he used NSNumber object wrapper.