Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.

SDK

- Xcode 9.0+

Framework

- Swift Standard Library

## Declaration

## Parameters

`other`

A sequence to compare to this sequence.

`areInIncreasingOrder`

A predicate that returns

`true`

if its first argument should be ordered before its second argument; otherwise,`false`

.

## Return Value

`true`

if this sequence precedes `other`

in a dictionary ordering as ordered by `are`

; otherwise, `false`

.

## Discussion

The predicate must be a *strict weak ordering* over the elements. That is, for any elements `a`

, `b`

, and `c`

, the following conditions must hold:

Note

This method implements the mathematical notion of lexicographical ordering, which has no connection to Unicode. If you are sorting strings to present to the end user, use `String`

APIs that perform localized comparison instead.

Complexity: O(*m*), where *m* is the lesser of the length of the sequence and the length of `other`

.

`are`

is alwaysIn Increasing Order(a, a) `false`

. (Irreflexivity)If

`are`

andIn Increasing Order(a, b) `are`

are bothIn Increasing Order(b, c) `true`

, then`are`

is alsoIn Increasing Order(a, c) `true`

. (Transitive comparability)Two elements are

*incomparable*if neither is ordered before the other according to the predicate. If`a`

and`b`

are incomparable, and`b`

and`c`

are incomparable, then`a`

and`c`

are also incomparable. (Transitive incomparability)