Prompt Title: Swift .map vs .forEach

In Swift, both .map and .forEach are higher-order functions that are used to perform operations on arrays or collections. However, they have different time complexities and therefore different Big O notations.

1. .map in Swift:

The .map function in Swift creates a new array by applying a given closure to each element in the original array. The closure is a function that takes an element from the original array and returns a transformed element to be included in the resulting array.

The time complexity of .map in Swift is O(n), where 'n' is the number of elements in the original array. This is because the closure is applied to each element in the array exactly once, resulting in a linear relationship between the size of the input array and the time taken to complete the operation.

2. .forEach in Swift:

The .forEach function in Swift is used to perform an action on each element of an array without creating a new array. It takes a closure as an argument and applies it to each element in the array.

The time complexity of .forEach in Swift is also O(n), where 'n' is the number of elements in the array. This is because the closure is applied to each element in the array exactly once, resulting in a linear relationship between the size of the input array and the time taken to complete the operation.

It's worth mentioning that while both .map and .forEach have the same time complexity, .map creates a new array with transformed elements, while .forEach only performs an action on each element without creating a new array. Therefore, if you need to create a new array with transformed elements, you should use .map, and if you only need to perform an action on each element without creating a new array, you can use .forEach.