SimpleTextField+Binding.swift

//: A UIKit based Playground for presenting user interface
  
import SwiftUI
import UIKit
import PlaygroundSupport
import Combine

class ObservingSource: BindableObject {
  var someString: String = ""
  var willChange = PassthroughSubject<String,Never>()
  let subscriber = PassthroughSubject<String, Never>()
  var cancelable: Cancellable?
  
  // You can totally make this a generic BTW
  public func someStringBinding() -> Binding<String> {
      return Binding(
          getValue: {
            self.someString
          },
          setValue: {
            self.subscriber.send($0)
            self.someString = $0
          }
      )
  }
  
  init () {
    cancelable = subscriber.print().makeConnectable().connect()
  }
}

struct SimpleTextField: View {
  
  @EnvironmentObject var observingSource: ObservingSource
  @State var textFieldString: String = ""
  var body: some View {
    VStack {
      TextField("Title", text: observingSource.someStringBinding())
    }
  }
}

let view = SimpleTextField().environmentObject(ObservingSource())
let viewController = UIHostingController(rootView: view)
PlaygroundPage.current.liveView = viewController
PlaygroundPage.current.needsIndefiniteExecution = true