Now that we have an array, how do we retrieve an individual value? This is where index comes into play.

An index refers to an item’s position within an ordered list. Arrays in Swift are zero-indexed, meaning the first item has index 0, the second index 1, and so on.

For example, suppose we have a String array with all the vowels:

var vowels = ["a", "e", "i", "o", "u"]

• The item at index 0 is "a".
• The item at index 1 is "e".
• The item at index 2 is "i".
• The item at index 3 is "o".
• The item at index 4 is "u".

To retrieve individual elements, we can use the subscript syntax, array[index]. The subscript syntax uses square brackets, [ ], around an index value.

For example:

print(vowels[0])     // Prints: a
print(vowels[1])     // Prints: e
print(vowels[2])     // Prints: i
print(vowels[3])     // Prints: o
print(vowels[4])     // Prints: u