Optimising in Swift – 50x Speedup From One Keyword Change

I did some work on some code presented at Swift London and could both improve the way it read by changing to a more functional style and using GCD and speed it up by about 18x in the core solver function.

I got a 50x speedup changing from a class to a struct ( before that my version was slower than the original using NSMutable arrays to store the objects.

The blog post has more details but I wanted to add this to give more context than the title.