Same language, different platform - searching for synergy between iOS and Vapor

Being able to share code between an iOS app and a backend running server-side Swift was one of the first things I thought about when Swift went open source. It’s been a common argument for choosing a server-side Swift framework ever since, although there’s been little focus on what is actually possible. With this talk I will dive into the current possibilities and limitations for sharing code between iOS and Vapor and I will look ahead and discus how this might change in the future.

Transcript

1. Same language,
   different platform
   Searching for synergy between iOS and Vapor
   SwiftConf 2018
   

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2. !
   

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3. • " Head of Vapor Development at Nodes
   • # Background in iOS development
   • $ Full time Vapor developer since January 2017
   • % ~50 customer projects and ~40 packages
   • & On the hunt for synergy..
   @steffendsommer
   

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4. '
   

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6. “Platform support for all Apple platforms as well as
   Linux”
   

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9. • ( A web framework built in Swift
   • ) Official support for SQLite, MySQL, PostgreSQL and Redis
   • * Built on top of SwiftNIO
   

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10. import Vapor
    let app = try Application()
    let router = try app.make(Router.self)
    router.get("hello") { req in
    return "Hello, world."
    }
    try app.run()
    

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11. • + Strong, safe and modern language
    • , Fast and has a low memory footprint (aka. -)
    • ♻ Potential synergy between iOS and Vapor
    • / Tech awesomeness
    

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12. • * Modern and Swifty API’s
    • 0 Great community
    • 1 Growing eco system
    • 2 Most popular
    

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13. 3
    • 4 Everything is “new”
    • ( Tooling
    • ⚙ Foundation
    • 1 Eco system
    • 6 Resources
    

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15. –Wikipedia
    “Synergy is the creation of a whole that is greater than the
    simple sum of its parts.”
    

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17. ☁
    # JSON
    Models Models
    Errors Errors
    Validation Validation
    Endpoints Endpoints
    

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18. ☁
    # JSON
    Models Models
    Errors Errors
    Validation Validation
    Endpoints Endpoints
    

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19. ☁
    #
    ♻
    Models
    Errors
    Validation
    Endpoints
    JSON
    

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20. ⏱
    

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23. " 9
    

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24. " 9
    ♻
    

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25. :
    

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27. ;
    

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28. #
    “Can I get an endpoint which return
    a list of subcategories?”
    “Yes.. it’s ready now”
    “Wait a sec, that endpoint gives
    me product categories?”
    “Oh.. so you want
    categories to be returned?”
    

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29. <
    

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30. • ⏱ To save time (write once, use twice)
    • "9 To share work-load
    • : To keep code in sync across platforms
    • ; To share knowledge about implementation
    • < To hide the data interchange format
    

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32. =
    

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33. final class Work: Codable {
    enum Kind: String, Codable {
    // ..
    }
    enum Framework: String, Codable {
    // ..
    }
    var id: Int?
    var company: String
    var companyLogoUrl: String
    var location: String
    var kind: Kind
    var framework: Framework
    var remoteAllowed: Bool
    var title: String
    var description: String
    var externalUrl: String
    var contactEmail: String
    var approvedAt: Date?
    var createdAt: Date?
    var updatedAt: Date?
    var deletedAt: Date?
    init(
    company: String,
    companyLogoUrl: String,
    location: String,
    kind: Kind,
    framework: Framework,
    remoteAllowed: Bool,
    title: String,
    description: String,
    externalUrl: String,
    contactEmail: String
    ) {
    // ..
    }
    }
    

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34. #
    struct Work: Codable {
    enum Kind: String, Codable {
    // ..
    }
    enum Framework: String, Codable {
    // ..
    }
    var id: Int?
    var company: String
    var companyLogoUrl: String
    var location: String
    var kind: Kind
    var framework: Framework
    var remoteAllowed: Bool
    var title: String
    var description: String
    var externalUrl: String
    var contactEmail: String
    var approvedAt: Date?
    var createdAt: Date?
    var updatedAt: Date?
    var deletedAt: Date?
    }
    

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35. ♻
    public final class Work: Codable {
    public enum Kind: String, Codable {
    // ..
    }
    public enum Framework: String, Codable {
    // ..
    }
    public var id: Int?
    public var company: String
    public var companyLogoUrl: String
    public var location: String
    public var kind: Kind
    public var framework: Framework
    public var remoteAllowed: Bool
    public var title: String
    public var description: String
    public var externalUrl: String
    public var contactEmail: String
    public var approvedAt: Date?
    public var createdAt: Date?
    public var updatedAt: Date?
    public var deletedAt: Date?
    public init(
    company: String,
    companyLogoUrl: String,
    location: String,
    kind: Kind,
    framework: Framework,
    remoteAllowed: Bool,
    title: String,
    description: String,
    externalUrl: String,
    contactEmail: String
    ) {
    // ..
    }
    }
    

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36. ⚠
    

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37. enum WorkError: Error {
    case noWorkAvailable
    }
    extension WorkError: AbortError {
    var identifier: String {
    return "noWork"
    }
    var status: HTTPResponseStatus {
    return .custom(code: 499, reasonPhrase: "No work available")
    }
    var reason: String {
    return "Unfortunately, no work available at this moment."
    }
    }
    

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38. #
    enum WorkError: Error {
    case noWork
    }
    extension WorkError {
    init?(from statusCode: Int) {
    switch statusCode {
    case 499: self = .noWork
    default: return nil
    }
    }
    }
    

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39. ♻
    enum APIError: Error {
    case noWorkAvailable
    var httpCode: UInt {
    switch self {
    case .noWorkAvailable: return 499
    }
    }
    init?(from httpCode: UInt) {
    switch httpCode {
    case 499: self = .noWorkAvailable
    default: return nil
    }
    }
    }
    

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40. ?
    

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41. public func routes(_ router: Router) throws {
    let api = router.grouped("api")
    let workAPIController = APIWorkController()
    api.get("/work", use: workAPIController.workList)
    api.get("/work", Work.parameter, use: workAPIController.work)
    }
    enum EnvironmentKey {
    enum Project {
    static let url = "PROJECT_URL"
    }
    }
    

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42. #
    struct WorkAPIService {
    enum Environment: String {
    case production = "http://serversideswift.work"
    }
    let environment: Environment
    func work(complete: @escaping ([Work]) -> ()) {
    sendRequest(to: "\(environment.rawValue)/api/work/") { (work: [Work]) in
    complete(work)
    }
    }
    func work(for id: Int, complete: @escaping (Work) -> ()) {
    sendRequest(to: "\(environment.rawValue)/api/work/\(id)") { (work: Work) in
    complete(work)
    }
    }
    }
    

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43. ♻
    public enum API {
    public enum Environment: String {
    case production = "http://serversideswift.work"
    func url(to endpoint: Endpoint) -> String {
    return self.rawValue + endpoint.path
    }
    }
    public enum Endpoint {
    case workList
    case work(Int)
    var path: String {
    switch self {
    case .workList: return "/api/work"
    case .work(let id): return "/api/work/\(id)"
    }
    }
    }
    }
    

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44. ☂
    

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45. final class APIWorkController {
    func workList(_ req: Request) throws -> Future<[Work]> {
    return Work
    .query(on: req)
    .filter(\.approvedAt != nil)
    .sort(\.approvedAt, .descending)
    .all()
    .thenThrowing { items in
    guard items.count > 0 else {
    throw WorkError.noWorkAvailable
    }
    return items
    }
    }
    func work(_ req: Request) throws -> Future {
    return try req.parameters.next(Work.self)
    }
    }
    

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46. #
    struct WorkAPIService {
    let environment: API.Environment
    func work(complete: @escaping ([Work]) -> ()) {
    sendRequest(to: environment.url(to: .workList)) { (work: [Work]) in
    complete(work)
    }
    }
    func work(for id: Int, complete: @escaping (Work) -> ()) {
    sendRequest(to: environment.url(to: .work(id))) { (work: Work) in
    complete(work)
    }
    }
    func sendRequest(to url: String, complete: @escaping (C) -> ()) {
    guard let url = URL(string: url) else { return }
    let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
    guard
    let dataResponse = data,
    let urlResponse = response as? HTTPURLResponse,
    error == nil
    else { return }
    do {
    let decoder = JSONDecoder()
    decoder.dateDecodingStrategy = .iso8601
    let results = try decoder.decode(C.self, from: dataResponse)
    complete(results)
    } catch let parsingError {
    print("Error", parsingError)
    }
    }
    task.resume()
    }
    }
    

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47. ♻
    public protocol HTTPClient {
    func sendRequest(to url: String, complete: @escaping (C) -> ())
    }
    public struct APIClient {
    internal let client: HTTPClient
    internal let environment: API.Environment
    public init(client: HTTPClient, environment: API.Environment) {
    self.client = client
    self.environment = environment
    }
    public func work(complete: @escaping ([Work]) -> ()) {
    client.sendRequest(to: environment.url(to: .workList)) { (work: [Work]) in
    complete(work)
    }
    }
    public func work(for id: Int, complete: @escaping (Work) -> ()) {
    client.sendRequest(to: environment.url(to: .work(id))) { (work: Work) in
    complete(work)
    }
    }
    }
    

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48. A
    

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49. • = Models
    • ⚠ Errors
    • ✅ Validation
    • ? Endpoints & Environments
    • C Business logic
    • D Styling
    • E Test code (e.g. mocks)
    • F Frameworks used in both places
    • ☂ A framework that wraps the endpoints
    

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50. ♻
    ☁
    #
    my-app-ios my-app-vapor
    my-app-shared
    

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52. G
    • # Copy files from shared repo into your project
    • $ Copy files from shared repo into your project
    

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53. H
    • # Add submodule and drag files into project
    • $ Add submodule and re-generate Xcode project file
    

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54. <
    • # Use SPM to pull down dependences and use this trick*
    to generate an iOS project. Alternatively use SwiftXcode.
    • $ Add the shared repo as a dependency
    * https://www.ralfebert.de/ios-examples/xcode/ios-dependency-management-with-swift-package-manager/
    

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55. I
    • # Check in Xcode project on shared repo and add the
    dependency to your Cartfile
    • $ N/A
    

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56. • G Copy and paste
    • H Git submodules
    • < Swift Package Manager
    • I Carthage
    • ☕ CocoaPods
    

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57. • K A change most likely requires platform-specific updates
    • L Both platforms would still have to sync and deploy/release
    • ☁ Code might depend on something that doesn’t run on the
    other platform
    • M Potential overhead in abstracting code that can be shared
    • N Not great until SPM gets integrated in Xcode
    3
    

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58. O
    

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59. • < Swift Package Manager integrated in Xcode
    • P Fluent on iOS
    • $ Vapor on iOS
    • Q Examples/resources/tools/frameworks
    • R Swift on Android
    

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60. • $ https://docs.vapor.codes
    • S https://discord.gg/vapor
    • T https://www.serversideswift.info
    • U Tim Condon - Getting Started with Server Side Swift and
    Vapor (Codemobile 2018)
    • 9 https://www.serversideswift.work
    

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61. V
    Any questions?
    @steffendsommer
    

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