RxSwift merge different kind of Observables
In case you want to merge two observables but you don't need the value of Element
and want a way to get rid of the Expression of type 'AnyObject' is unused
when using the .map { $0 as AnyObject }
option:
var a = PublishSubject<Int>()
var b = PublishSubject<Void>()
let observable = Observable.merge(a.map { _ in return Void() }, b)
To merge
them, they need to have the same type for their Element
.
So, one option is to throw away their type information and cast to AnyObject
. Now they can be merged:
let stringSubject = PublishSubject<String>()
let stringObservable = stringSubject.asObservable().map { $0 as AnyObject }
let intSubject = PublishSubject<Int>()
let intObservable = intSubject.asObservable().map { $0 as AnyObject }
Observable.of(stringObservable, intObservable).merge()
.subscribeNext { print($0) }
.addDisposableTo(disposeBag)
stringSubject.onNext("a")
stringSubject.onNext("b")
intSubject.onNext(1)
intSubject.onNext(2)
stringSubject.onNext("c")
Output:
a
b
1
2
c
Another option would be to wrap then in an enum:
enum Container {
case S(String)
case I(Int)
}
let stringSubject = PublishSubject<String>()
let stringObservable = stringSubject.asObservable().map { Container.S($0) }
let intSubject = PublishSubject<Int>()
let intObservable = intSubject.asObservable().map { Container.I($0) }
Observable.of(stringObservable, intObservable).merge()
.subscribeNext { e in
switch e {
case .S(let str):
print("next element is a STRING: \(str)")
case .I(let int):
print("next element is an INT: \(int)")
}
}
.addDisposableTo(disposeBag)
stringSubject.onNext("a")
stringSubject.onNext("b")
intSubject.onNext(1)
intSubject.onNext(2)
stringSubject.onNext("c")
Output:
next element is a STRING: a
next element is a STRING: b
next element is an INT: 1
next element is an INT: 2
next element is a STRING: c
As for the other operators that can combine Observable
s of varying types (like zip
and combineLatest
), none work quite like merge
. However, check those out. They might be better suited to your requirements.