---
title: "contains(_:)"
framework: combine
role: symbol
role_heading: Instance Method
path: "combine/publisher/contains(_:)"
---

# contains(_:)

Publishes a Boolean value upon receiving an element equal to the argument.

## Declaration

```swift
func contains(_ output: Self.Output) -> Publishers.Contains<Self>
```

## Parameters

- `output`: An element to match against.

## Return Value

Return Value A publisher that emits the Boolean value true when the upstream publisher emits a matching value.

## Discussion

Discussion Use contains(_:) to find the first element in an upstream that’s equal to the supplied argument. The contains publisher consumes all received elements until the upstream publisher produces a matching element. Upon finding the first match, it emits true and finishes normally. If the upstream finishes normally without producing a matching element, this publisher emits false and finishes. In the example below, the contains(_:) operator emits true the first time it receives the value 5 from the numbers.publisher, and then finishes normally. let numbers = [-1, 5, 10, 5] numbers.publisher     .contains(5)     .sink { print("\($0)") }

// Prints: "true"

## See Also

### Applying matching criteria to elements

- [contains(where:)](combine/publisher/contains(where:).md)
- [tryContains(where:)](combine/publisher/trycontains(where:).md)
- [allSatisfy(_:)](combine/publisher/allsatisfy(_:).md)
- [tryAllSatisfy(_:)](combine/publisher/tryallsatisfy(_:).md)