Use Lazy Collections in Swift

Written by Team Kodeco

A lazy collection is a collection that delays operations until they are needed. This can be useful when working with large data sets, as it allows you to perform operations on the data while minimizing memory usage and improving performance.

In Swift, the LazyMapCollection and LazyFilterCollection types are provided for working with lazy collections. These types can be used to perform operations such as mapping and filtering on a collection without creating a new array to store the results.

Here is an example of using a LazyMapCollection to square the elements of an array:

let numbers = [1, 2, 3, 4, 5]
let squaredNumbers = numbers.lazy.map { $0 * $0 }
print(squaredNumbers) // LazyMapCollection<Array<Int>, Int>

As you can see, the squaredNumbers variable is of type LazyMapCollection<Array<Int>, Int> and not an array of squared numbers. The mapping isn’t performed until the collection is accessed.

print(Array(squaredNumbers)) // [1, 4, 9, 16, 25]

In the above example, calling Array(squaredNumbers) forces the lazy collection to perform the mapping and return the result as an array.

It’s important to note that Lazy Collections aren’t always the best option, it depends on the use case and the size of the collection. In some cases, a simple for loop may be more efficient than using a Lazy Collection. But for large collections, using Lazy Collections can be a powerful tool for improving performance and memory usage.