Understanding How Bubble Sort Works

In this lesson you will learn how to implement bubble sort in Swift, so you understand sorting from the ground up. This is for anyone searching for "Swift bubble sort implementation".

Bubble sort is a simple algorithm that repeatedly compares two neighbouring values and swaps them if they are in the wrong order. The name comes from the way larger bubbles gradually rise to the surface.

The sample code uses nested for loops; the inner loop compares the neighbouring elements arr[j] and arr[j + 1] and swaps them with the dedicated arr.swapAt(j, j + 1) method when they are out of order. Notice how concisely Swift expresses that swap.

A common stumbling block for beginners is that it is not efficient in terms of computational complexity. You will almost never write it yourself in production code, but it is the standard first step in learning algorithms.

In practice you would use an optimised implementation such as the sorted method, but this remains an important algorithm for understanding what happens internally.