Instance Method

firstIndex(of:)

Returns the first index where the specified value appears in the collection.

Declaration

func firstIndex(of element: UTF16.CodeUnit) -> Int?

Parameters

element

An element to search for in the collection.

Return Value

The first index where element is found. If element is not found in the collection, returns nil.

Discussion

After using firstIndex(of:) to find the position of a particular element in a collection, you can use it to access the element by subscripting. This example shows how you can modify one of the names in an array of students.

var students = ["Ben", "Ivy", "Jordell", "Maxime"]
if let i = students.firstIndex(of: "Maxime") {
    students[i] = "Max"
}
print(students)
// Prints "["Ben", "Ivy", "Jordell", "Max"]"

Complexity: O(n), where n is the length of the collection.