Presenter.swift

//
//  Presenter.swift
//
//  Created by Daniel Tartaglia on 8/24/20.
//  Copyright © 2020 Daniel Tartaglia. MIT License.
//

import UIKit
import RxSwift

extension UIViewController {
    @discardableResult
    func present<T>(_ create: @autoclosure () -> (UIViewController, Observable<T>), animated: Bool) -> Observable<T> {
        let (controller, action) = create()
        present(controller, animated: animated)
        let dismissed = PublishSubject<Void>()
        let sharedAction = action.share(replay: 1)
        _ = sharedAction
            .observeOn(MainScheduler.instance)
            .subscribe(onCompleted: { [weak self, weak controller] in
                if self?.presentedViewController == controller {
                    self?.dismiss(animated: true, completion: {
                        dismissed.onCompleted()
                    })
                }
                else {
                    dismissed.onCompleted()
                }
            })
        return Observable.combineLatest(sharedAction, dismissed.startWith(())).map { $0.0 }
    }
}

func scene<Action, VC: UIViewController>(name: String, type: VC.Type, binder: (VC) -> Observable<Action>) -> (UIViewController, Observable<Action>) {

    let storyboard = UIStoryboard(name: name, bundle: nil)
    let controller = storyboard.instantiateInitialViewController() as! VC
    controller.loadViewIfNeeded()
    return (controller, binder(controller))
}