Making Meetup 6.0

This month, Paul Bruneau and Matthew Bischoff will talk about "Making Meetup 6.0". They'll walk us through the architecture underlying the new Meetup iOS app, rewritten entirely in Swift, as well as how they employed view models, protocols, generics, unit tests, and other patterns to build an app that's fun to work on and easy to change.

Transcript

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2. MAKING MEETUP
   

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3. Matthew Bischoff (@mb) • Lickability
   Paul Bruneau (@ethicalpaul) • Meetup
   

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4. THE HISTORY
   

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6. MEETUP 6.0
   

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8. THE GOAL
   COMPLETELY REDESIGN THE IOS
   EXPERIENCE OF MEETUP
   

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9. REWRITE OR
   RE-SKIN?
   

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10. WHY REWRITE?
    > Legacy Objective-C codebase
    > Completely new design
    > New APIs (v 3.0)
    > New team
    > Swift
    

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11. HOW LONG?
    

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12. HOW LONG?
    LONGER THAN WE
    THOUGHT
    

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13. HOW LONG?
    LONGER THAN WE
    THOUGHT
    A FEW TIMES
    

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14. WAS IT THE
    RIGHT CALL?
    WE THINK SO.
    

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15. THE CODE
    

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16. MacBookRetina:Meetup mb$ cloc .
    1250 text files.
    1202 unique files.
    339 files ignored.
    http://cloc.sourceforge.net v 1.64 T=4.36 s (208.9 files/s, 21111.0 lines/s)
    -------------------------------------------------------------------------------
    Language files blank comment code
    -------------------------------------------------------------------------------
    Swift 771 20479 20124 48891
    JSON 134 0 0 2194
    Objective C 2 46 15 137
    C/C++ Header 4 61 74 59
    -------------------------------------------------------------------------------
    SUM: 911 20586 20213 51281
    -------------------------------------------------------------------------------
    

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17. USE LIBRARIES
    BUT ISOLATE
    THEM
    

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18. platform :ios, '9.0'
    source 'https://github.com/CocoaPods/Specs.git'
    use_frameworks!
    target 'Meetup' do
    pod 'RealmSwift', '~> 1.1.0'
    pod 'Alamofire', '~> 3.5.0'
    pod 'SocketRocket', '~> 0.5.0'
    pod 'SwiftyJSON', :git => 'https://github.com/Navdy/SwiftyJSON.git', :branch => 'xcode8b6'
    pod 'BuddyBuildSDK', '~> 1.0.12'
    pod 'RMStore', '~> 0.7'
    pod 'Static', git: 'https://github.com/venmo/Static.git'
    pod 'CLTokenInputView', '~> 2.3.0'
    pod 'KeychainAccess', '~> 2.4.0'
    pod 'XLForm', '~> 3.1.1'
    pod '1PasswordExtension', '~> 1.8'
    pod 'FormatterKit/TimeIntervalFormatter', '~> 1.8'
    pod 'Nuke', '~> 3.2.0'
    pod 'KVOController', '~> 1.1.0'
    pod 'BRYHTMLParser', '~> 2.1.0'
    pod 'AcknowList', :git => 'https://github.com/vtourraine/AcknowList.git', :branch => 'swift-2-3'
    pod 'ReachabilitySwift', '~> 2.4.0'
    pod 'NSAttributedString+CCLFormat', '~> 1.2.0'
    pod 'NYTPhotoViewer/Core', '~> 1.1.0'
    pod 'RSKGrowingTextView', '~> 1.2.0'
    pod 'Google/SignIn', '~> 2.0.3'
    pod 'FBSDKLoginKit', '~> 4.16'
    pod 'UIColor_Hex_Swift', :git => 'https://github.com/yeahdongcn/UIColor-Hex-Swift.git', :branch => 'Swift-2.3'
    pod 'DeepLinkKit', '~> 1.2.1'
    target 'MeetupTests' do
    inherit! :search_paths
    pod 'OHHTTPStubs', '~> 5.0.0'
    end
    end
    

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19. KEY DEPENDENCIES
    > Persistence
    > RealmSwift
    > Networking
    > Alamofire
    > JSON Parsing
    > SwiftyJSON
    

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20. PATTERNS
    > Storyboards, size classes, stack views, auto layout
    > private and final by default
    > Document anything internal or public
    > Protocols define interfaces
    > Dependencies are injected
    > Logic is unit tested (1403 tests)
    

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21. TYPES
    MANY SMALL TYPES THAT DO FEW THINGS
    

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22. MODEL
    HOLDS DATA AND MODELS BUSINESS LOGIC
    

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23. /// Model representing a location where Meetups may take place.
    final class Location: Object {
    // MARK: - Public API
    /// The name of the city.
    dynamic var name = ""
    /// The full name of the city, as returned by query search, if applicable.
    dynamic var fullName: String?
    // MARK: - LocationGenerating
    var city: String { return name }
    /// The state which contains the city, if applicable.
    dynamic var state = ""
    /// The ISO_3166-1 country code for the country which contains the city.
    dynamic var country = ""
    /// Localized name of country based on request's language information.
    dynamic var localizedCountryName: String?
    /// The latitude of the city.
    dynamic var latitude: Double = kCLLocationCoordinate2DInvalid.latitude
    /// The longitude of the city.
    dynamic var longitude: Double = kCLLocationCoordinate2DInvalid.longitude
    /// The zip code of the city. For cities in countries without ZIP codes, a placeholder will be returned.
    dynamic var zipCode = ""
    }
    extension Location: NSCoding {
    …
    }
    

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24. REQUEST
    DESCRIBES AN API REQUEST IN TERMS OF THE DOMAIN
    

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25. /// An enum encapsulating types of location requests.
    enum LocationRequest: MeetupRequest {
    /// Request locations nearby a specified set of coordinates.
    case ByCoordinate(coordinate: CLLocationCoordinate2D, bearerToken: String?, pageSize: Int)
    /// Request locations corresponding to a queried city name or zip code.
    case ByQuery(query: String, bearerToken: String?)
    /// Request the authenticated or pre-registation user's current country.
    case Country(bearerToken: String?)
    // MARK: - MeetupRequest
    var path: String? {
    switch self {
    case .ByCoordinate, .ByQuery:
    return "find/locations"
    case .Country:
    return "members/self"
    }
    }
    var parameters: [String: AnyObject]? {
    switch self {
    case let ByCoordinate(coordinate, _, pageSize):
    return ["lat": coordinate.latitude, "lon": coordinate.longitude, "page": pageSize]
    case let ByQuery(query, _):
    return ["query": query]
    case .Country:
    return ["only": "country"]
    }
    }
    var URLRequest: NSURLRequest {
    if let bearerToken = bearerToken {
    return defaultRequestWithPreRegistrationAuthorizationHeader(bearerToken: bearerToken)
    } else {
    return defaultURLRequest()
    }
    }
    }
    

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26. UPDATER
    MAKES A NETWORK REQUEST, PERSISTS INFORMATION, CALLS COMPLETION
    

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27. /// Downloads objects related to nearby location requests.
    final class LocationUpdater {
    typealias Completion = (result: Result<[Location]>) -> Void
    /// The bearer token used to create authenticated requests.
    private let bearerToken: String?
    init(bearerToken: String? = nil) {
    self.bearerToken = bearerToken
    }
    func fetchLocationsNearby(coordinate: CLLocationCoordinate2D, pageSize: Int = 10, completion: Completion) {
    let request = LocationRequest.ByCoordinate(coordinate: coordinate, bearerToken: bearerToken, pageSize: pageSize)
    performLocationRequest(request, completion: completion)
    }
    func fetchLocationsMatchingQuery(query: String, completion: Completion) {
    let request = LocationRequest.ByQuery(query: query, bearerToken: bearerToken)
    performLocationRequest(request, completion: completion)
    }
    func fetchCountry(completion: (result: Result) -> Void) {
    let request = LocationRequest.Country(bearerToken: bearerToken)
    NetworkController.request(request).responseObject { (request, response, result: Result) in
    completion(result: result)
    }
    }
    private func performLocationRequest(locationRequest: LocationRequest, completion: Completion) {
    NetworkController.request(locationRequest).responseObject { (_, _, result: Result<[Location]>) in
    completion(result: result)
    }
    }
    }
    

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28. PARSER
    TRANSFORMS JSON INTO MODELS
    

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29. /// Parses a `Location` object from a JSON dictionary, or `nil` if no identifier is found.
    struct LocationParser: Parser {
    static func parse(dictionaryRepresentation: [String : AnyObject]) -> Location? {
    let JSONObject = JSON(dictionaryRepresentation)
    let location = Location()
    location.name = JSONObject["city"].stringValue
    location.fullName = JSONObject["name_string"].string
    location.localizedCountryName = JSONObject["localized_country_name"].string
    location.state = JSONObject["state"].stringValue
    location.country = JSONObject["country"].stringValue
    location.zipCode = JSONObject["zip"].stringValue
    if let latitude = JSONObject["lat"].double, longitude = JSONObject["lon"].double {
    location.latitude = latitude
    location.longitude = longitude
    }
    return location
    }
    }
    extension Location: Parseable {
    typealias ParserType = LocationParser
    }
    

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30. VIEW MODEL
    MODELS ONLY THE VIEW NEEDS TO DISPLAY AND FORMAT
    

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31. /// The view model containing all view-related data necessary to lay out an `LocationCell`.
    struct ViewModel {
    /// The configuration style for the cell based on a specified location status.
    enum LocationStatus {
    /// Cell configuration for an unknown location.
    case Unknown
    case Known(location: Location?, style: DisplayStyle)
    private var title: String {
    switch self {
    case .Unknown:
    return NSLocalizedString("Current location", comment: "…")
    case let .Known(_, style):
    return style.title
    }
    }
    private var image: UIImage {
    switch self {
    case .Unknown:
    return UIImage(named: "LocationServices")!
    case let .Known(_, style):
    return style.image
    }
    }
    }
    /// The location status for which to configure the cell.
    let locationStatus: LocationStatus
    }
    

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32. DATA SOURCE
    TABLE AND COLLECTION VIEW DATA SOURCES AS SEPARATE OBJECTS
    

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33. /// A data source object that acts as the table view data source for nearby locations, or optionally a loading interface.
    final class LocationDataSource : NSObject, UITableViewDataSource {
    /// An enum representing the table section. Do not initialize directly. Instead, call `sectionForSectionIndex`.
    enum Section {
    /// The section when a loading indicator is displayed.
    case Loading
    /// The section containing a cell displaying the user's current device location.
    case CurrentLocation(rows: [Meetup.LocationDataSource.CurrentLocationRow])
    /// The section containing locations nearby the user's current location.
    case NearbyLocations(rows: [Meetup.LocationDataSource.LocationRow])
    /// The number of rows in the section.
    var numberOfRows: Int { get }
    }
    typealias CellConfiguration = (tableView: UITableView,
    indexPath: NSIndexPath,
    section: Section,
    authorizationStatus: CLAuthorizationStatus?) -> UITableViewCell
    init(loading: Bool, cellConfiguration: CellConfiguration)
    func sectionForSectionIndex(index: Int) -> Meetup.LocationDataSource.Section?
    }
    

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34. CELL CREATOR
    TAKES MODELS AND PRODUCES CELLS FOR THE DATA SOURCE
    

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35. /// Sets up the table view and creates configured cells for location editing.
    final class LocationCellCreator {
    init(tableView: UITableView) {
    tableView.registerNibForClass(LoadingCell.self, reuseIdentifier: self.dynamicType.LoadingCellIdentifier)
    …
    }
    func cell(tableView: UITableView,
    indexPath: NSIndexPath,
    section: LocationDataSource.Section,
    authorizationStatus: CLAuthorizationStatus?) -> UITableViewCell {
    let cell: UITableViewCell?
    switch section {
    case .Loading:
    cell = loadingCell(tableView: tableView, indexPath: indexPath)
    }
    return cell
    }
    }
    // MARK: - Private methods
    private func currentLocationCell(tableView tableView: UITableView,
    indexPath: NSIndexPath,
    authorizationStatus: CLAuthorizationStatus?,
    location: Location?,
    isNearOtherLocations: Bool,
    isOnboarding: Bool) -> UITableViewCell { … }
    private func onboardingLocationCell(tableView tableView: UITableView,
    indexPath: NSIndexPath) -> UITableViewCell { … }
    }
    

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36. WHAT WE LEARNED
    > The best way to learn Swift is to write a lot of it
    > Lack of refactoring makes architecture more important
    > Doing all-swift removed inter-op challenges
    > Swift 2.2 -> 2.3 migration went smoothly
    > Compile times are still terrible
    

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37. AND FINALLY...
    

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38. YOU CAN HIRE
    CAN HIRE YOU
    

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39. THANK YOU
    WE’D LOVE TO ANSWER YOUR
    QUESTIONS
    — @MB AND @ETHICALPAUL
    

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