bidirectional-bind-full.swift

let textFull = BehaviorRelay<String?>(value: nil)
let textFirst = BehaviorRelay<String?>(value: nil)
let textSecond = BehaviorRelay<String?>(value: nil)
    
    
typealias ItemType = (current: String, previous: String)

Observable.combineLatest(textFirst.map({ $0 ?? "" }).currentAndPrevious(), textSecond.map({ $0 ?? "" }).currentAndPrevious(), textFull.map({ $0 ?? "" }).currentAndPrevious())
      .filter({ (first: ItemType, second: ItemType, full: ItemType) -> Bool in
        return "\(first.current) \(second.current)" != full.current && "\(first.current)" != full.current
      })
      .subscribe(onNext: { (first: ItemType, second: ItemType, full: ItemType) in
        if first.current != first.previous || second.current != second.previous {
          textFull.accept("\(first.current) \(second.current)")
        }
        else if (full.current != full.previous) {
          let items = full.current.components(separatedBy: " ")
          let firstName = items.count > 0 ? items[0] : ""
          let lastName = items.count > 1 ? items[1] : ""

          if firstName != first.current {
            textFirst.accept(firstName)
          } else if lastName != second.current {
            textSecond.accept(lastName)
          }
        }
      })
      .disposed(by: disposeBag)


(textFieldFirst.rx.text <-> textFirst).disposed(by: disposeBag)
(textFieldSecond.rx.text <-> textSecond).disposed(by: disposeBag)
(textFieldFull.rx.text <-> textFull).disposed(by: disposeBag)