Instance Method


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


func firstIndex(of element: UInt8) -> Int?



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.


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"
// Prints "["Ben", "Ivy", "Jordell", "Max"]"

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

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