How to combine three Signals using reactive cocoa in swift?

Question

I have read the documentation, it looks like "and" isn't suitable to combine signals. Then, I have looked into "combineLatest" but it expects atleast one value is returned from each signal. My use case, is I have three separate signals, they have no relation among them. I just want to combine them altogether and observe in one place and handle accordingly inside the closure.

For example:

Signal1<Int, NoError>
Signal2<String, NoError>
Signal3<SomeType, NoError>

Combine3Signals<(Int, String, SomeType), NoError>.observeValues {...//handle accordingly based on type...}

score 6 · Accepted Answer · answered Apr 13 '18 at 18:29

You can use Signal.merge for that, but first you have to convince the Compiler that you actually want to merge those different types

let p1 = MutableProperty<Int>(1)
let p2 = MutableProperty<Bool>(false)
let p3 = MutableProperty<String>("")

let s1: Signal<Any, NoError> = p1.signal.map { $0 }
let s2: Signal<Any, NoError> = p2.signal.map { $0 }
let s3: Signal<Any, NoError> = p3.signal.map { $0 }

let merged = Signal<Any, NoError>.merge(s1, s2, s3)
merged.observeValues { print($0) }


p1.value = 2
p1.value = 3
p3.value = "Hello"
p2.value = true

Without the map, the compiler will complain

error: cannot convert value of type 'Signal<Int, NoError>' to specified type 'Signal<Any, NoError>'

How to combine three Signals using reactive cocoa in swift?

1 Answers1