Reactive+UISearchController.swift

import UIKit
import RxSwift
import RxCocoa

extension Reactive where Base: UISearchController {
    var searchResultUpdater: DelegateProxy<UISearchController, UISearchResultsUpdating> {
        return RxSearchResultUpdatingProxy.proxy(for: base)
    }
    
    var queryText: Observable<String> {
        return Observable
            .merge(Observable.just(""), RxSearchResultUpdatingProxy.proxy(for: base).didUpdateSearchResultsSubject.map { $0.searchBar.text ?? "" })
            .distinctUntilChanged()
    }
}

class RxSearchResultUpdatingProxy: DelegateProxy<UISearchController, UISearchResultsUpdating>, DelegateProxyType, UISearchResultsUpdating {
    static func currentDelegate(for object: UISearchController) -> UISearchResultsUpdating? {
        return object.searchResultsUpdater
    }
    
    static func setCurrentDelegate(_ delegate: UISearchResultsUpdating?, to object: UISearchController) {
        object.searchResultsUpdater = delegate
    }
    
    static func registerKnownImplementations() {
        register { RxSearchResultUpdatingProxy(searchController: $0) }
    }
    
    init(searchController: UISearchController) {
        super.init(parentObject: searchController, delegateProxy: RxSearchResultUpdatingProxy.self)
    }
    
    let didUpdateSearchResultsSubject = PublishSubject<UISearchController>()
    
    func updateSearchResults(for searchController: UISearchController) {
        _forwardToDelegate?.updateSearchResults(for: searchController)
        didUpdateSearchResultsSubject.onNext(searchController)
    }
    
    deinit {
        didUpdateSearchResultsSubject.onCompleted()
    }
}