Generic Instance Method

zip(_:_:_:_:)

Combines elements from three other publishers and delivers a transformed output.

Declaration

func zip<P, Q, R, T>(_ publisher1: P, _ publisher2: Q, _ publisher3: R, _ transform: @escaping (Self.Output, P.Output, Q.Output, R.Output) -> T) -> Publishers.Map<Publishers.Zip4<Self, P, Q, R>, T> where P : Publisher, Q : Publisher, R : Publisher, Self.Failure == P.Failure, P.Failure == Q.Failure, Q.Failure == R.Failure

Parameters

publisher1

A second publisher.

publisher2

A third publisher.

publisher3

A fourth publisher.

transform

A closure that receives the most recent value from each publisher and returns a new value to publish.

Return Value

A publisher that uses the transform closure to emit new elements, produced by combining the most recent value from four upstream publishers.

Discussion

The returned publisher waits until all four publishers have emitted an event, then delivers the oldest unconsumed event from each publisher as a tuple to the closure. For example, if publisher P1 emits elements a and b, and publisher P2 emits elements c and d, and publisher P3 emits the elements e and f, and publisher P4 emits the event g, the transform closure receives the tuple (a, c, e, g). The closure won’t receive a tuple with elements b, d, or f until P4 emits another event. If any upstream publisher finishes successfully or fails with an error, the zipped publisher does the same.

See Also

Combining Elements from Multiple Publishers

func combineLatest<P, T>(P, (Self.Output, P.Output) -> T) -> Publishers.Map<Publishers.CombineLatest<Self, P>, T>

Subscribes to an additional publisher and invokes a closure upon receiving output from either publisher.

func combineLatest<P>(P) -> Publishers.CombineLatest<Self, P>

Subscribes to an additional publisher and publishes a tuple upon receiving output from either publisher.

func combineLatest<P, Q, T>(P, Q, (Self.Output, P.Output, Q.Output) -> T) -> Publishers.Map<Publishers.CombineLatest3<Self, P, Q>, T>

Subscribes to two additional publishers and invokes a closure upon receiving output from any of the publishers.

func combineLatest<P, Q>(P, Q) -> Publishers.CombineLatest3<Self, P, Q>

Subscribes to two additional publishers and publishes a tuple upon receiving output from any of the publishers.

func combineLatest<P, Q, R, T>(P, Q, R, (Self.Output, P.Output, Q.Output, R.Output) -> T) -> Publishers.Map<Publishers.CombineLatest4<Self, P, Q, R>, T>

Subscribes to three additional publishers and invokes a closure upon receiving output from any of the publishers.

func combineLatest<P, Q, R>(P, Q, R) -> Publishers.CombineLatest4<Self, P, Q, R>

Subscribes to three additional publishers and publishes a tuple upon receiving output from any of the publishers.

func merge(with: Self) -> Publishers.MergeMany<Self>

Combines elements from this publisher with those from another publisher of the same type, delivering an interleaved sequence of elements.

func merge<P>(with: P) -> Publishers.Merge<Self, P>

Combines elements from this publisher with those from another publisher, delivering an interleaved sequence of elements.

func merge<B, C>(with: B, C) -> Publishers.Merge3<Self, B, C>

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

func merge<B, C, D>(with: B, C, D) -> Publishers.Merge4<Self, B, C, D>

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

func merge<B, C, D, E>(with: B, C, D, E) -> Publishers.Merge5<Self, B, C, D, E>

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

func merge<B, C, D, E, F>(with: B, C, D, E, F) -> Publishers.Merge6<Self, B, C, D, E, F>

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

func merge<B, C, D, E, F, G>(with: B, C, D, E, F, G) -> Publishers.Merge7<Self, B, C, D, E, F, G>

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

func merge<B, C, D, E, F, G, H>(with: B, C, D, E, F, G, H) -> Publishers.Merge8<Self, B, C, D, E, F, G, H>

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

func zip<P>(P) -> Publishers.Zip<Self, P>

Combines elements from another publisher and deliver pairs of elements as tuples.

func zip<P, T>(P, (Self.Output, P.Output) -> T) -> Publishers.Map<Publishers.Zip<Self, P>, T>

Combines elements from another publisher and delivers a transformed output.

func zip<P, Q>(P, Q) -> Publishers.Zip3<Self, P, Q>

Combines elements from two other publishers and delivers groups of elements as tuples.

func zip<P, Q, T>(P, Q, (Self.Output, P.Output, Q.Output) -> T) -> Publishers.Map<Publishers.Zip3<Self, P, Q>, T>

Combines elements from two other publishers and delivers a transformed output.

func zip<P, Q, R>(P, Q, R) -> Publishers.Zip4<Self, P, Q, R>

Combines elements from three other publishers and delivers groups of elements as tuples.