Migrate MXParallaxHeader Delegates to RxSwift observables

MXParallaxHeader_RxExtension.swift

extension Reactive where Base: MXParallaxHeader {
    
    public var delegate: DelegateProxy<MXParallaxHeader, MXParallaxHeaderDelegate> {
        return MXParallaxHeaderDelegateProxy.proxy(for: base)
    }

    var parallaxHeaderDidScroll: ControlEvent<MXParallaxHeader> {
        let source: Observable<MXParallaxHeader> = self.delegate.methodInvoked(#selector(MXParallaxHeaderDelegate.parallaxHeaderDidScroll(_:))).map { (parameters) in
            (parameters[0] as? MXParallaxHeader ?? MXParallaxHeader())
        }
          return ControlEvent.init(events: source)
    }
}

MXParallaxHeader_RxImpl.swift

  scrollView.parallaxHeader.rx
            .parallaxHeaderDidScroll
            .subscribe(onNext: { i in
                print("progress \(i.progress)")
            })
        .disposed(by: disposeBag)

MXParallaxHeaderDelegateProxy.swift

class MXParallaxHeaderDelegateProxy: DelegateProxy<MXParallaxHeader, MXParallaxHeaderDelegate>, DelegateProxyType, MXParallaxHeaderDelegate {
    
    public weak private(set) var mxParallaxHeader: MXParallaxHeader?
      
    public init(mxParallaxHeader: ParentObject) {
        self.mxParallaxHeader = mxParallaxHeader
        super.init(parentObject: mxParallaxHeader, delegateProxy: MXParallaxHeaderDelegateProxy.self)
    }
    
    static func registerKnownImplementations() {
        self.register { MXParallaxHeaderDelegateProxy(mxParallaxHeader: $0) }
    }
    
    static func currentDelegate(for object: MXParallaxHeader) -> MXParallaxHeaderDelegate? {
        return object.delegate
    }
    
    static func setCurrentDelegate(_ delegate: MXParallaxHeaderDelegate?, to object: MXParallaxHeader) {
        object.delegate = delegate
    }
}