Swift speed

I can guess you opened this book because you are interested in speed and are probably wondering, "How fast can Swift be?" Before you even start learning Swift and discovering all the good things about it, let's answer it right here and right now.

Let's take an array of 100,000 random numbers; sort it in Swift, Objective-C, and C using the standard sort function from stdlib (sort in Swift, qsort in C, and compare in Objective-C); and measure how much time each would take.

Sorting an array with 100,000 integer elements gives us this:

Technology	Time taken
Swift	0.00600 sec
C	0.01396 sec
Objective-C	0.08705 sec

And the winner is, Swift! Swift is 14.5 times faster than Objective-C and 2.3 times faster than C.

In other examples and experiments, C is usually faster than Swift and Swift is way faster than Objective-C. These measurements were done with Xcode 7.0 beta 6 and Swift 2.0. It's important to highlight that the improvements in Swift 2.0 were mainly focused on making it cleaner, more powerful, safer, and more stable, and preparing it for open sourcing. Swift's performance hasn't reached its full potential yet, and the future is so exciting!