RxSwift: Use Zip with different type observables

GDanger picture GDanger · Dec 4, 2015 · Viewed 13.8k times · Source

I'm using RxSwift 2.0.0-beta

How can I combine 2 observables of different types in a zip like manner?

// This works
[just(1), just(1)].zip { intElements in
    return intElements.count
}

// This doesn't
[just(1), just("one")].zip { differentTypeElements in 
    return differentTypeElements.count
}

The current workaround I have is to map everything to an optional tuple that combines the types, then zips optional tuples into a non-optional one.

    let intObs = just(1)
        .map { int -> (int: Int?, string: String?) in
            return (int: int, string: nil)
    }
    let stringObs = just("string")
        .map { string -> (int: Int?, string: String?) in
        return (int: nil, string: string)
    }
    [intObs, stringObs].zip { (optionalPairs) -> (int: Int, string: String) in
        return (int: optionalPairs[0].int!, string: optionalPairs[1].string!)
    }

That's clearly pretty ugly though. What is the better way?

Answer

Wonjung Kim picture Wonjung Kim · Dec 4, 2015

This works for me. I tested it in Xcode7, RxSwift-2.0.0-beta

zip(just(1), just("!")) { (a, b) in 
    return (a,b)
}