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

# merge(with:_:_:)

Combines elements from this publisher with those from three other publishers, delivering an interleaved sequence of elements.

## Declaration

```swift
func merge<B, C, D>(with b: B, _ c: C, _ d: D) -> Publishers.Merge4<Self, B, C, D> where B : Publisher, C : Publisher, D : Publisher, Self.Failure == B.Failure, Self.Output == B.Output, B.Failure == C.Failure, B.Output == C.Output, C.Failure == D.Failure, C.Output == D.Output
```

## Parameters

- `b`: A second publisher.
- `c`: A third publisher.
- `d`: A fourth publisher.

## Return Value

Return Value A publisher that emits an event when any upstream publisher emits an event.

## Discussion

Discussion Use merge(with:_:_:) when you want to receive a new element whenever any of the upstream publishers emits an element. To receive tuples of the most-recent value from all the upstream publishers whenever any of them emit a value, use combineLatest(_:_:_:). To combine elements from multiple upstream publishers, use zip(_:_:_:). In this example, as merge(with:_:_:) receives input from the upstream publishers, it republishes the interleaved elements to the downstream: let pubA = PassthroughSubject<Int, Never>() let pubB = PassthroughSubject<Int, Never>() let pubC = PassthroughSubject<Int, Never>() let pubD = PassthroughSubject<Int, Never>()

cancellable = pubA     .merge(with: pubB, pubC, pubD)     .sink { print("\($0)", terminator: " " )}

pubA.send(1) pubB.send(40) pubC.send(90) pubD.send(-1) pubA.send(2) pubB.send(50) pubC.send(100) pubD.send(-2)

// Prints: "1 40 90 -1 2 50 100 -2 " The merged publisher continues to emit elements until all upstream publishers finish. If an upstream publisher produces an error, the merged publisher fails with that error.

## See Also

### Republishing elements from multiple publishers as an interleaved stream

- [merge(with:)](combine/publisher/merge(with:)-7fk3a.md)
- [merge(with:)](combine/publisher/merge(with:)-7qt71.md)
- [merge(with:_:)](combine/publisher/merge(with:_:).md)
- [merge(with:_:_:_:)](combine/publisher/merge(with:_:_:_:).md)
- [merge(with:_:_:_:_:)](combine/publisher/merge(with:_:_:_:_:).md)
- [merge(with:_:_:_:_:_:)](combine/publisher/merge(with:_:_:_:_:_:).md)
- [merge(with:_:_:_:_:_:_:)](combine/publisher/merge(with:_:_:_:_:_:_:).md)