RxSwift error example

ChallengeViewController.swift

//
//  ChallengeViewController.swift
//  WinninApp
//
//  Created by Flávio Caetano on 9/26/16.
//  Copyright © 2016 Winnin. All rights reserved.
//

import UIKit
import RxSwift
import RxCocoa
import RxDataSources


class ChallengeViewController: UIViewController {
    private struct Constants {
        struct CellIdentifiers {
            static let Indicator = "IndicatorCell"
            static let Contestant = "ContestantCell"
        }
    }
    
    var challenge: ChallengeViewModel!
    var challengeId: Int64!
    
    private let player = RxPlayer()
    private let screen = ChallengeScreen()
    private let disposeBag = DisposeBag()
    
    private let itemsDataSource = RxTableViewSectionedAnimatedDataSource<ElementSection<ChallengeScreen.DataContent>>()
    
    // MARK: Outlets
    @IBOutlet private weak var titleLabel: UILabel!
    @IBOutlet private weak var imageView: UIImageView!
    @IBOutlet private weak var tableView: UITableView!
    
    @IBOutlet private weak var downVoteButton: UIButton!
    @IBOutlet private weak var upVoteButton: UIButton!
    
    @IBOutlet private weak var errorLabel: UILabel!
    

    override func viewDidLoad() {
        super.viewDidLoad()
        
        player.playbackLoops = true
        player.addToViewController(self) { view in
            self.view.insertSubview(view, atIndex: 0)
        }

        loadChallenge()
            .driveNext { [weak self] challenge in
                self?.titleLabel.text = challenge.title
                self?.imageView.sd_setImageWithURL(challenge.contestants.first?.image)
                
                if let videoURL = challenge.contestants.first?.video {
                    self?.player.setUrl(videoURL)
                }
            }
            .addDisposableTo(disposeBag)
        
        // Expand
        tableView.rx_modelSelected(ChallengeScreen.DataContent.self)
            .filter { [weak self] in $0 == .Indicator(.Count(self?.challenge.viewCount ?? 0)) }
            .subscribeNext { [weak self] _ in _ = try? self?.screen.expandItems() }
            .addDisposableTo(disposeBag)
        
        // Contract
        tableView.rx_modelSelected(ChallengeScreen.DataContent.self)
            .filter { $0 == .Indicator(.Contract) }
            .subscribeNext { [weak self] _ in _ = try? self?.screen.contractItems() }
            .addDisposableTo(disposeBag)
        
        
        screen.items
            .bindTo(tableView.rx_itemsWithDataSource(itemsDataSource)) { tableView, indexPath, item in
                switch item {
                case .Contestant(let contestant):
                    let cell = tableView.dequeueReusableCellWithIdentifier(Constants.CellIdentifiers.Contestant, forIndexPath: indexPath) as! ContestantTableViewCell
                    cell.contestant = contestant
                    
                    return cell
                    
                case .Indicator(let indicator):
                    let cell = tableView.dequeueReusableCellWithIdentifier(Constants.CellIdentifiers.Indicator, forIndexPath: indexPath) as! ChallengeIndicatorTableViewCell
                    cell.indicator = indicator
                    
                    return cell
                }
            }
            .addDisposableTo(disposeBag)
        
        // Player
        player.rx_ready
            .bindTo(player.rx_playbackFromBeginning)
            .addDisposableTo(disposeBag)
        
        player.rx_playbackState
            .map { $0 != .Failed }
            .bindTo(errorLabel.rx_hidden)
            .addDisposableTo(disposeBag)
    }
}


// MARK: - Private Methods
extension ChallengeViewController {
    private func loadChallenge() -> Driver<ChallengeViewModel> {
        if let challenge = self.challenge {
            return Driver.just(challenge)
        }
        
        return screen.loadChallenge(challengeId)
            .doOnNext { [weak self] in self?.challenge = $0 }
            .driveShowError(self)
    }
}