[RxSwift] Custom ControlProperty

쓰기만 가능한 속성은 Binder로, 읽기와 쓰기가 모두 가능해야 한다면 Control Property로 구현한다.

구현 방법

    /// This is a separate method to better communicate to public consumers that
    /// an `editingEvent` needs to fire for control property to be updated.
    internal func controlPropertyWithDefaultEvents<T>(
        editingEvents: UIControl.Event = [.allEditingEvents, .valueChanged],
        getter: @escaping (Base) -> T,
        setter: @escaping (Base, T) -> Void
        ) -> ControlProperty<T> {
        return controlProperty(
            editingEvents: editingEvents,
            getter: getter,
            setter: setter
        )
    }

• controlPropertyWithDefaultEvents 호출
• 파라미터로 getter, setter 전달
  • setter은 옵저버로, 즉 바인딩될 때 사용

1. Reactive extension

2. base.rx.controlProperty

3. getter, setter 구현

extension Reactive where Base: UISlider {
    var color: ControlProperty<UIColor?> {
        return base.rx.controlProperty(editingEvents: .valueChanged, getter: {
            (slider) in
            UIColor(white: CGFloat(slider.value), alpha: 1.0)
        }, setter: { slider, color in
            var white = CGFloat(1)
            color?.getWhite(&white, alpha: nil)
            slider.value = Float(white)
        })
    }
}

class CustomControlPropertyViewController: UIViewController {
    
    let bag = DisposeBag()
    
    @IBOutlet weak var resetButton: UIBarButtonItem!
    
    @IBOutlet weak var whiteSlider: UISlider!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
//        whiteSlider.rx.value
//            .map { UIColor(white: CGFloat($0), alpha: 1.0) }
//            .bind(to: view.rx.backgroundColor)
//            .disposed(by: bag)
//        
//        resetButton.rx.tap
//            .map { Float(0.5) }
//            .bind(to: whiteSlider.rx.value)
//            .disposed(by: bag)
//        
//        resetButton.rx.tap
//            .map { UIColor(white: 0.5, alpha: 1.0) }
//            .bind(to: view.rx.backgroundColor)
//            .disposed(by: bag)
        
        whiteSlider.rx.color
            .bind(to: view.rx.backgroundColor)
            .disposed(by: bag)
        
        resetButton.rx.tap
            .map { _ in UIColor(white: 0.5, alpha: 1.0) }
            .bind(to: whiteSlider.rx.color.asObserver(), view.rx.backgroundColor.asObserver())
            .disposed(by: bag)
    }
}

• asObserver()은 명시적 타입 변환(컴파일 에러 방지)