Swift vs Obj-C Performance Comparison

Is Swift faster than Objective-C? This question has been asked so many times and the answer is still unclear. So I took the recent Xcode 7.3 beta and ran some tests comparing Swift 2.2 and Objective-C. The results were surprising even for me.

I found many tests proving that Swift is faster than Objective-C and some saying old Obj-C is swifter than Swift. The truth is in the middle. Straight out in some cases Swift is much faster, but Obj-C still has some advantages.

In tests, I use native data structures for Swift (like `Array`, `Dictionary` and `Set`) and Objective-C (it means `NSArray`, `NSDictionary` and `NSSet`). I also use `XCTest`’s `measureBlock` in both tests. It is pretty easy and available for Swift and Obj-C. The tests run with standard Release optimization, because it is well known that Swift is much slower than Obj-C in debug.

The metodology I use is fair. All data structures are filled with one million elements (`String` or` NSString` with next or randomized numbers) and I run each test 10 times (in fact tests run 10 times in each run by default, so it means they run 100 times).

Arrays

A basic and the most popular data structure in almost all programming languages. Furthermore it is really fast in Swift.

Sets

Unfortunately `Set` is not faster than `NSSet`. In fact it is two times slower when adding and removing elements.

Access operation means here `contains()` function.

Dictionaries

This really useful data structure is similar in both languages. Adding is slower in Swift, but then you can enumerate faster through it.

Conclusion

I would like to say Swift is faster, but I cannot. It is not slower at all, but also is not three times faster like Apple is saying. Although it does not mean we should go back to Obj-C. Swift is more comfortable – lets you do more with less work needed to do. In addition to cool features like strong typing and generics makes it perfect choice.

I am going to run more tests and compare different loops and sets more precisely (like `intersect` and `union` funcs) in the next few weeks. Looking forward to see you soon!