Instance MethodSwift

firstIndex(of:)

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

Available because Self conforms to Collection.
Available when Self.Element conforms to Equatable

func firstIndex(of element: Self.Element) -> Self.Index?

Parameters

element: An element to search for in the collection.

Returns

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

Overview

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"]"