RxSwift常见操作

never

never就是创建一个sequence，但是不发出任何事件信号。

let disposeBag: DisposeBag()
let neverObservable = Observable<String>.never()
        
        neverObservable.subscribe { (event:Event<String>) in
            
            print(event.element ?? "")
            
        }.disposed(by: disposeBag)

结果是什么都不打印

empty

empty就是创建一个空的sequence,只能发出一个completed事件

let disposeBag: DisposeBag()
let emptyObservable = Observable<String>.empty()
        
        emptyObservable.subscribe { (event:Event<String>) in
            
            print(event)
            
        }.disposed(by: disposeBag)

completed

just

just是创建一个sequence只能发出一种特定的事件，能正常结束

let disposeBag: DisposeBag()
let justObservable = Observable.just("justObservable")
        
        justObservable { (event:Event<String>) in
            
            print(event)
            
        }.disposed(by: disposeBag)

next(justObservable)
completed

of

of是创建一个sequence能发出很多种事件信号

let disposeBag: DisposeBag()
let ofObservable = Observable.of("1","2","3","4")
        
        ofObservable.subscribe { (event:Event<String>) in
            
            print(event)
            
        }.disposed(by: disposeBag)

next(1)
next(2)
next(3)
next(4)
completed

from

from就是从集合中创建sequence，例如数组，字典或者Set

let disposeBag: DisposeBag()
let fromObservable = Observable.from(["a":"1","b":"2"])
        
        fromObservable.subscribe { (event) in
            
            print(event)
            
        }.disposed(by: disposeBag)

next((key: "b", value: "2"))
next((key: "a", value: "1"))
completed

create

我们也可以自定义可观察的sequence，那就是使用create

let disposeBag: DisposeBag()
let creatObservable = Observable.create { (observer:AnyObserver<Any>) -> Disposable in
            
            observer.onNext("123")
            observer.onNext(1.44)
            observer.onCompleted()
            return Disposables.create()
        }
        creatObservable.subscribe { (event:Event<Any>) in
            print(event)
        }.disposed(by: disposeBag)

next(123)
next(1.44)
completed

range

range就是创建一个sequence，他会发出这个范围中的从开始到结束的所有事件

let disposeBag: DisposeBag()
let rangeObservable = Observable.range(start: 1, count: 10)
        
        rangeObservable.subscribe { (event) in
            
            print(event)
            
        }.disposed(by: disposeBag)

next(1)
next(2)
next(3)
next(4)
next(5)
next(6)
next(7)
next(8)
next(9)
next(10)
completed

repeatElement

创建一个sequence，发出特定的事件n次

let disposeBag: DisposeBag()
let repeatElementObservable = Observable.repeatElement("repeatElement")
        
        repeatElementObservable.take(4).subscribe { (event) in
            print(event)
        }.disposed(by: disposeBag)

next(repeatElement)
next(repeatElement)
next(repeatElement)
next(repeatElement)
completed