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My second talk at @iosconfsg on behalf of @worldlinexpert was all about how Swift KeyPaths can be leveraged to build some pretty effective syntax and patterns. Here's a thread that recaps some of the key ideas ⤵️ 
Swift 4 has introduced a new construct called KeyPaths, which allow to defer calls to the getter or setter of a property. They essentially perform the same job than a closure would, but with less $0 hanging around!
While they don't look like much by themselves, I want to show you that with a little bit of extra code, KeyPaths can be used to unlock some very nice and clean syntax!
For instance, you can define wrappers over standard methods, like map and sorted, in order to make them accept a KeyPath rather than a closure as their argument.
But you can take it even one step further, by defining a helper function (or operator) that will transform KeyPaths into getter functions. This way, every method in the standard library that expects a getter closure can now be called with a KeyPath instead 🎉
We can keep going further, and leverage KeyPaths to implement a type-safe alternative to NSPredicate!
To reach this goal, all we are required to do is to define a Predicate type and provide some overloads for the standard operators to construct, combine and evaluate them.
The great thing is that, the more operators for which you provide overloads, the more you'll introduce nice new syntax to your codebase!
If you're curious about how this can be implemented for most of Swift operators, you can take a look at this GitHub project: github.com/vincent-pradei…
That's all for this thread! There's even more content in the full slide deck, so if you've liked what you just read, do check it out: github.com/vincent-pradei…
