Cocoa Programming for OS X: The Big Nerd Ranch Guide

For the More Curious: Functional Methods and Minimizing Closure Syntax

Although it is not a functional language, Swift has a number of features to support functional programming. In particular, the standard library includes the functions map, reduce, and filter. A full overview of these functions is beyond the scope of this book, but they can be very helpful in constructing clear code for common tasks.

Recall that the Employee class has a property, name, whose type is String?. Here’s how you might use these methods to create an array of all non-nil names:

let names = employees.filter({ employee in
    return employee.name != nil
}).map({ employee in
    return employee.name!
})

When the closure is the last parameter, however, the ...