just

1개의 항목을 방출하는 Observable 메서드

Observable.just(element)
    .subscribe { event in print(event) }
    .disposed(by: disposeBag)

Observable.just([1, 2, 3])
    .subscribe { event in print(event) }
    .disposed(by: disposeBag)

[1, 2, 3]을 방출하는 경우 [1, 2, 3]을 그대로 방출한다.

of

2개 이상의 요소를 방출하는 메서드

let apple = "🍏"
let orange = "🍊"
let kiwi = "🥝"
Observable.of(apple, orange, kiwi)
    .subscribe { event in print(event) }
    .disposed(by: disposeBag)

Observable.of([1, 2], [3, 4], [5, 6])
    .subscribe { event in print(event) }
    .disposed(by: disposeBag)

    public static func of(_ elements: Element ..., scheduler: ImmediateSchedulerType = CurrentThreadScheduler.instance) -> Observable<Element> {
        ObservableSequence(elements: elements, scheduler: scheduler)

타입메서드로 구현이 되어있으며 가변파라미터를 받는다.

from

let fruits = ["🍏", "🍎", "🍋", "🍓", "🍇"]
Observable.from(fruits)
    .subscribe { event in print(event) }
    .disposed(by: disposeBag)

요소를 순서대로 방출