RxSwift Glossary and Concepts

Do you speak RxSwift? Do you know the concepts, words and operators? Here is a snapshot summary of many of them.

Some of the RxSwift Concepts from Getting Started

An Observable is a definition of: 

  • “..how the sequence is generated..”
  • “..what parameters are used for element generation..”

Disposing

“..release all of the resources that were allocated to compute upcoming elements..”

Observable aka Sequence

  • One after another, the Observable sends a Next (element), Error, or a Completed
  • What stops them from coming? An Error, Completed or dispose the subscriptions.

Observer

Subscribes to Observables

Subject

(Source: Rx.playground)

Terse mode: “acts both as an Observer and as an Observable”

Full mode: “A Subject is a sort of bridge or proxy that is available in some implementations of ReactiveX that acts both as an observer and as an Observable. Because it is an observer, it can subscribe to one or more Observables, and because it is an Observable, it can pass through the items it observes by reemitting them, and it can also emit new items.”

Operators

There is a list sorted by functionality at https://github.com/ReactiveX/RxSwift/blob/master/Documentation/API.md#rxswift-supported-operators

Operator Types:

(Sources: Rx.playground and github docs)

  • Combination operators – startWithcombineLatestmergeswitchLatestzip; “Operators that work with multiple source Observables to create a single Observable”
  • Conditional and Boolean Operators – takeUntiltakeWhile – “Operators that evaluate one or more Observables or items emitted by Observables.”
  • Connectable Observable Operators – multicastreplay, replayAll, publish – “like an ordinary Observable yet only when its connect() is called does it emit”
  • Error Handling Operators- catchErrorretry – “Operators that help to recover from error notifications from an Observable.”
  • Filtering Observables – distinctUntilChanged, filtertake; “Operators that selectively emit items from a source Observable.”
  • Mathematical and Aggregate Operators – concat, reduce – “Operators that operate on the entire sequence of items emitted by an Observable”
  • Observable Utility Operators – doOn, subscribesubscribeNextsubscribeCompletedsubscribeError; “toolbox of useful Operators for working with Observables”
  • Transforming Observables – map / selectflatMapscan; “Operators that transform items that are emitted by an Observable”
  • Units – “purpose of Driver unit is to ensure the underlying observable sequence has the following properties”: It “can’t fail”, “main thread”, and more.

Schedulers

Schedulers are an abstraction away from what does work (queues / threads).

RxSwiftCommunity

By the way, the RxSwiftCommunity bears checking in on from time to time. Action is listed there and it comes up often in the RxSwift Slack community and at least once in Stack Overflow. Just like the adoption of RxSwift, I sense the community will grow over time.

Update: If one looks at the code commits done for the RxSwiftCommunity website, one can easily see lots of activity going on.

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