基础概念

• 一直在强调Observable Sequence
• 最简单的创建Sequence的方法
• Disposable：销毁时，可以在其中释放资源

_ = Observable<String>.create { observerOfString -> Disposable in
        print("This will never be printed")
        observerOfString.on(.next("😬"))
        observerOfString.on(.completed)
        return Disposables.create()
    }

使用Observable创建和订阅Sequence

• 默认提供和一些创建Sequence的方法：create、never、empty、just、of、from、repeatElement、generate、deferred、error、doOn、
• 具体概念请到 Rx.playground -> Creating_and_Subscribing_to_Observables中查看

使用Subject创建Sequence

• PublishSubject observers在订阅该类型信号开始，接受event
• ReplaySubject 创建时有个参数叫bufferSize，the specified bufferSize number of previous events to new subscribers.
• BehaviorSubject 这个不好解释，Broadcasts new events to all subscribers, and the most recent (or initial) value to new subscribers.
• Variable 对Subject的包装，使用.value赋值，相当于onNext

合并操作Combination Operators

• 提供用一些方法startWith、merge、zip、combineLatest、switchLatest
• 把一些单个数据合并到一起成为一个Observable信号

传输操作Transforming Operators

• 提供用一些方法map、flatMap、flatMapLatest、scan

过滤操作Filtering and Conditional Operators

• 提供用一些方法filter、distinctUntilChanged、elementAt、single、take、takeLatest、takeWhile、takeUntil、skip、skipWhile、skipWhileWithIndex、skipUntil

集合操作Mathematical and Aggregate Operators

• toArray

Observable.range(start: 1, count: 10)
        .toArray()
        .subscribe { print($0) }
        .addDisposableTo(disposeBag)

• reduce

Observable.of(10, 100, 1000)
        .reduce(1, accumulator: +)   // 求+运算，1+10+100+1000
        .subscribe(onNext: { print($0) })
        .addDisposableTo(disposeBag)

• contact

         let disposeBag = DisposeBag()
         let subject1 = BehaviorSubject(value: "🍎")
         let subject2 = BehaviorSubject(value: "🐶")
         let variable = Variable(subject1)
    
         variable.asObservable()
           .concat()
           .subscribe { print($0) }
           .addDisposableTo(disposeBag)
        subject1.onNext("🍐")
        subject1.onNext("🍊")

        variable.value = subject2
    
        subject2.onNext("I would be ignored")
        subject2.onNext("🐱")
    
        subject1.onCompleted()
    
        subject2.onNext("🐭")

    //  在subject1调用onCompleted()之前，subject2都收不到信号

可连接的操作Connectable Operators

• publish Converts the source Observable sequence into a connectable sequence. 将一般的�Observable Sequence转换为connectable sequence
• replay，新订阅开始前时，会收到bufferSize个之前的信号
• multicast，可以用一个interval携带多个observable sequence

错误处理机制Error Handling Operators

• catchErrorJustReturn("xxx") 不管返回什么错误都只传给订阅者一个"xxx"
• catchError 抓取到异常后，Recovers一个已有的Sequence
• retry(maxAttemptCount: Int) 得到错误返回后重试，maxAttemptCount为最大重试次数

调试Debugging Operators

• debug Prints out all subscriptions, events, and disposals.

Enable RxSwift.resourceCount

Follow these instructions to enable RxSwift.Resources.total in your project:

• CocoaPods

1. Add a post_install hook to your Podfile, e.g.:

    target 'AppTarget' do
    pod 'RxSwift'
    end

    post_install do |installer|
    installer.pods_project.targets.each do |target|
        if target.name == 'RxSwift'
            target.build_configurations.each do |config|
                if config.name == 'Debug'
                    config.build_settings['OTHER_SWIFT_FLAGS'] ||= ['-D', 'TRACE_RESOURCES']
                end
            end
        end
    end
end

2. Run pod update.
3. Build project (Product → Build).

• Carthage

1. Run carthage build --configuration Debug.
2. Build project (Product → Build).