Bindings over a CurrentValue subject allow you to use combine for side affects

CurrentValueSubjectToBinding.swift

//: [Previous](@previous)

import Foundation
import SwiftUI
import Combine

//: Current Value Subject is a value, a publisher and a subscriber all in one
let currentValueSubject = CurrentValueSubject<Bool, Never>(true)

print(currentValueSubject.value)

//: Bindings are used in SwiftUI to get and Set state, CurrentValueSubjects work well with Bindings
let binding = Binding<Bool>(
  get:{
    return currentValueSubject.value
},
  set:{
    currentValueSubject.send($0)
})


print("The Binding is NOT the value \(binding)\n see how it is an object not just Bool")

//: INstead to get the current value use `wrappedValue`
print("The Value is now \(binding.wrappedValue)")

//: Now Lets Set the binding to false to see how it affects the currentValueSubject
binding.wrappedValue = false
print("The Value is now \(binding.wrappedValue)")

//: The currentValueSubject can also send(_:) affecting the value displayed by the binding
currentValueSubject.send(true)
print("The Value is now \(binding.wrappedValue)")

//: Lets do something random and display the set

//: First lets create a stream that listens to the values of our currentValueSubject, lets maps the booleans to a string just for show
var allStrings: [String]?
let cancel = currentValueSubject.map({ (next) -> String in
    if next {
    return "Set To True"
  } else {
    return "Set To False"
  }
})
  //: Collect will hold all the values in an array until .finished is sent
  .collect().sink { (collectedStrings) in
  // Sink will set our array with the array collected when the currentValueSubject has finished
  allStrings = collectedStrings
}

//: Here we Set the binding 10 random times, run the playground more than once to check
for _ in 0..<10 {
  let randomBool = arc4random() % 2 == 0 // flip a coin ;)
  binding.wrappedValue = randomBool
}
//: Complete the stream, in a real app this might be from deallocation of an object that owns it for example
currentValueSubject.send(completion: .finished)
//: when you subscribe to the currentValue Subject it will send the latest value to the subscriber how many items do you expect in allStrings?
print("Number of items collected: \(allStrings!.count)")
//: Lets print all of the items out
print(allStrings!.joined(separator: ",\n"))

//: [Next](@next)

extension CurrentValueSubject {
  var binding: Binding<Output> {
    Binding(get: {
      self.value
    }, set: {
      self.send($0)
    })
  }
}

mySubject.binding