How to create MutableProperty from MutableProperty in Swift ReactiveCocoa 4

Question

Is there any easy way to create MutableProperty from MutableProperty in Swift ReactiveCocoa 4?

I have a case that, and I want an way to create classB with classA, in which I need to setup statusB with statusA, but how to do this?

class ClassA {
  var statusA = MutableProperty<T>
}

class ClassB {
    var statusB = MutableProperty<U>

    func getStatusB(from StatusA: T) -> U {
        // .. assume this is implemented.
    }

    init(statusB: U) {
        //...
    }

    convenience init(from classA: ClassA) {
        self.statusB = // here how to setup this value from classA's statusA with getStatusB(from:)?
    }
}

I found similar at https://github.com/ReactiveCocoa/ReactiveCocoa/issues/2183 — JerryZhou, Feb 09 '17 at 02:27
after map(..) MutableProperty become AnyProperty, but not MutableProperty — JerryZhou, Feb 09 '17 at 03:34

score 0 · Answer 1 · answered Apr 11 '17 at 19:20

you can't make a MutableProperty<U> directly from a MutableProperty<T> but you can make a MutableProperty<U> with initial value getStatusB(from: classA.statusA.value) and then bind it to classA.statusA.signal.map(getStatusB) so all changes to the MutableProperty<T> propagate to the MutableProperty<U>, like

convenience init(from classA: ClassA) {
    self.init(getStatusB(from: classA.statusA.value)))
    self.statusB <~ classA.statusA.signal.map(getStatusB)
}

(however for this to compile, getStatusB can't be an instance method of ClassB because you need to be able to call it before you call self.init)

How to create MutableProperty from MutableProperty in Swift ReactiveCocoa 4

1 Answers1