How do I take the last ten elements from an rx observable?

Question

I have an Observable that combine three other Observables then emit a single array. From this merged array I would like to take the last 10 objects. But I think I take the last ten arrays instead. Tried using compactMap first but that didn't do the trick. It's still returned as an array

return Observable.combineLatest(breakfast, dessert, cookies) { $0 + $1 + $2 }
    .compactMap { $0 }.takeLast(10)
    .do(onNext: { [weak self] value in
        self?.content.accept(value.compactMap {
            NewRecipesCollectionViewCellViewModel(recipe: $0)})
        })

Thanks, but it says that observable doesn't have an operator named that. — Joakim Sjöstedt, Oct 30 '20 at 23:50

serzso · Accepted Answer · 2020-11-02T10:57:19.750

With this approach you get back the elements one by one:

    let breakfast = Observable.just(["egg", "milk"])
    let dessert = Observable.just(["ice cream", "chocolate"])
    let cookies = Observable.just(["cookie1", "cookie2"])

    Observable.combineLatest(breakfast, dessert, cookies)
        .map { $0 + $1 + $2 }
        .do(onNext: { foods in
            let lastTenFood = foods.suffix(10) // returns the last 10 elements from the array
            for food in lastTenFood {
                print("Food: \(food)")
            }
        })
        .subscribe()
        .disposed(by: disposeBag)

How do I take the last ten elements from an rx observable?

1 Answers1