Instance Method

index(_:offsetBy:)

Returns an index that is the specified distance from the given index.

Declaration

func index(_ i: Int, offsetBy distance: Int) -> Int

Parameters

i

A valid index of the array.

distance

The distance to offset i.

Return Value

An index offset by distance from the index i. If distance is positive, this is the same value as the result of distance calls to index(after:). If distance is negative, this is the same value as the result of abs(distance) calls to index(before:).

Discussion

The following example obtains an index advanced four positions from an array’s starting index and then prints the element at that position.

let numbers = [10, 20, 30, 40, 50]
let i = numbers.index(numbers.startIndex, offsetBy: 4)
print(numbers[i])
// Prints "50"

The value passed as distance must not offset i beyond the bounds of the collection.

Relationships

From Protocol