My RxSwift Summary ②

Learn more about the features of RxSwift

This article is a continuation of My RxSwift Summary ①.

Features of RxSwift

There are two points to be aware of in asynchronous processing.

--Code execution order --How to handle shared mutable data

Is.

RxSwift addresses these issues by incorporating the following two concepts:

-Declarative programming → Example: If you define ʻa = b + c, the value of ʻa will be b and c. Update every time the value changes. -[Functional Programming](https://qiita.com/tail-island/items/1782e4c1e7b620a4f9c0#%E9%96%A2%E6%95%B0%E5%9E%8B%E3%82%82%E3% 81% 84% E3% 81% 84% E3% 81% 91% E3% 81% A9% E3% 82% AA% E3% 83% 96% E3% 82% B8% E3% 82% A7% E3% 82% AF% E3% 83% 88% E6% 8C% 87% E5% 90% 91% E3% 82% 82% E3% 81% AD) → A method of describing processing by a series of function input / output

And I have the following five features. (= [Reactive System](https://thinkit.co.jp/article/9185#:~:text=%E3%83%AA%E3%82%A2%E3%82%AF%E3%83%86 % E3% 82% A3% E3% 83% 96% E3% 82% B7% E3% 82% B9% E3% 83% 86% E3% 83% A0% E3% 81% A8% E3% 81% AF% E3 % 80% 81% E3% 81% B2% E3% 81% A8% E3% 81% 93% E3% 81% A8% E3% 81% A7% E8% A8% 80% E3% 81% 86% E3% 81 % A8% E3% 80% 8C% E5% 8D% B3% E5% BF% 9C,% E3% 80% 8D% E3% 81% A7% E3% 81% 99% EF% BC% 88% E5% 9B% B31% EF% BC% 89% E3% 80% 82)))

--Responsive → Always reflect the latest state of the application in the UI --Resilient → Each process is separated and error recovery is easy. --Elastic → Lazy loading for Variable workload % E9% 81% 85% E5% BB% B6% E8% AA% AD% E3% 81% BF% E8% BE% BC% E3% 81% BF) and [Throttle](https: // future-architect) .github.io/articles/20200121/), resource sharing and other features --Message-driven → Communicate between components asynchronously using message-based communication, loosely coupled for better reusability, and implemented separately from the class lifecycle

RxSwift components

RxSwift has three components: ʻObservable / operator / scheduler`.

Observable An observable object defined by ʻObservable `. A series of events that stream an invariant snapshot (a copy of the data at that moment) of a series of data generated over time. Can be generated asynchronously.

Multiple ʻobservers can react to events in real time to update the UI and use data. ʻObservableType protocol can generate the following three events.

--next → Event that brings the next data to ʻobserver. Keep bringing the value to ʻobserver until completed occurs. --completed → End a series of events with success and notify the observer. --ʻError → Notify that ʻobservable ended with ʻerror`.

Operators ʻObservable contains a number of methods (ʻOperators) that perform asynchronous, event-based processing. Since these produce only the output without the Side effect (which is reflected in the UI on the user side), you can combine ʻOperator to convert the input to any value. To name a typical ʻOperator,

--filter → Extract only the values that meet the conditions --Perform processing for all values that flowed in map → ʻObservable --skip` → Skip a specific value

And so on. (I'll summarize it in another article later.)

Scehduler Scheduler is similar to Dispatch queue, and processing can be divided into main thread and sub thread. RxSwift has a lot of predefined Schedulers, so it's convenient!

• UI update is done in the main thread

RxCocoa RxSwift is about common use of Rx, not just Swift. UIKit etc. peculiar to Swift will be handled using RxCocoa. RxCocoa is a library that adds reactive functionality to many ʻUI parts`.