Swift version: 5.4. The map() method allows us to transform arrays (and indeed any kind of collection) using a transformation closure we specify. The return value will be an array of the same size, containing your transformed elements.

What is map and flatMap in Swift?

So map transforms an array of values into an array of other values, and flatMap does the same thing, but also flattens a result of nested collections into just a single array. … In fact, mapping is a much more general concept, that can be applied in many more situations than just when transforming arrays.

How does swift implement map?

1. take an array and return another array.
2. need a closure parameter to perform the transformation step.
3. use a trusty for loop and build up an output array.