Instance Method

# first(where:)

Returns the first element of the sequence that satisfies the given predicate.

## Parameters

`predicate`

A closure that takes an element of the sequence as its argument and returns a Boolean value indicating whether the element is a match.

## Return Value

The first element of the sequence that satisfies `predicate`, or `nil` if there is no element that satisfies `predicate`.

## Discussion

The following example uses the `first(where:)` method to find the first negative number in an array of integers:

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

### Finding Elements

`func contains(where: ((key: Key, value: Value)) -> Bool) -> Bool`

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

`func allSatisfy(((key: Key, value: Value)) -> Bool) -> Bool`

Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.

`func firstIndex(where: ((key: Key, value: Value)) -> Bool) -> Index?`

Returns the first index in which an element of the collection satisfies the given predicate.

`func min(by: ((key: Key, value: Value), (key: Key, value: Value)) -> Bool) -> (key: Key, value: Value)?`

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

`func max(by: ((key: Key, value: Value), (key: Key, value: Value)) -> Bool) -> (key: Key, value: Value)?`

Returns the maximum element in the sequence, using the given predicate as the comparison between elements.