Swift Code Patterns

An updated version of my older Code Patterns talk.

This talk starts of reviewing small recommendations and works it's way up to talking about extensions (including some examples taken from recent projects) and then finally about larger design patterns including: Dependency Injection, Launch/Debug Menus and Many DataSources / Scenarios.

Transcript

1. Swift Code Patterns
   May 12, 2016 • Mike Zornek
   

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2. Introductions
   

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7. Questions, anytime.
   

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8. What’s Inside?
   

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9. NSLocalizedString()
   

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10. NSLocalizedString("Job Request",
    comment: "header text for information regarding a job")
    

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11. NSLocalizedString("shopping-cart.create-order.button",
    comment: "Title for footer button in Shopping Cart")
    

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12. TODO Comments
    

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13. // TODO: Add proper error handling.
    

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14. // TODO: Add proper error handling.
    // https://github.com/bignerdranch/project-x/issues/39
    

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15. DRY
    

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16. Storyboards
    

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17. struct AppNameStoryboards {
    static func logInStoryboard() -> UIStoryboard {
    return UIStoryboard(name: "LogIn", bundle: nil)
    }
    }
    // LoginViewController.swift
    private struct Segue {
    static let PINSetup = "showPinSetup"
    static let RetrieveUsername = "showRetrieveUsername"
    static let ResetPassword = "showResetPassword"
    static let ResendActivationLink = "showResendActivationLink"
    }
    

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18. Filenames
    URLs
    Preference Names
    JSON keys
    

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19. Extensions
    

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20. UIColor
    

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21. Forgive my
    indentation.
    

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22. let c1 = UIColor.redColor()
    let c2 = UIColor(hue: 0.8,
    saturation: 0.8,
    brightness: 0.8,
    alpha: 1.0)
    let c3 = UIColor(red: 50/255,
    green: 25/255,
    blue: 32/255,
    alpha: 255/255)
    let c4 = UIColor(hex: 0xE6A024)
    

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23. public extension UIColor {
    convenience init(hex: UInt32) {
    let red = CGFloat((hex >> 16) & 0xff) / 255
    let green = CGFloat((hex >> 8) & 0xff) / 255
    let blue = CGFloat((hex ) & 0xff) / 255
    self.init(red: red, green: green, blue: blue, alpha: 1)
    }
    }
    

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24. public extension UIColor {
    convenience init(bnr_hex: UInt32) {
    let red = CGFloat((hex >> 16) & 0xff) / 255
    let green = CGFloat((hex >> 8) & 0xff) / 255
    let blue = CGFloat((hex ) & 0xff) / 255
    self.init(red: red, green: green, blue: blue, alpha: 1)
    }
    }
    bnr_hex
    

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25. struct DayTheme {
    static let backgroundColor = UIColor(hex: 0xfefefe)
    static let textColor = UIColor(hex: 0x121212)
    static let highlightColor = UIColor.redColor()
    }
    greetingLabel.textColor = DayTheme.textColor
    

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26. UITableView
    

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27. let cell =
    tableView.dequeueReusableCellWithIdentifier("CustomCell",
    forIndexPath: indexPath) as! CustomCell
    let cell = tableView.dequeue(cellOfType: CustomCell.self,
    indexPath: indexPath)
    

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28. extension UITableView {
    func dequeue(cellOfType type: V.Type,
    indexPath: NSIndexPath, reuseIdentifier: String? = nil) -> V {
    let identifier = reuseIdentifier ?? String(type)
    return dequeueReusableCellWithIdentifier(identifier,
    forIndexPath: indexPath) as! V
    }
    }
    String(type) // old way NSStringFromClass(type)
    

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29. Custom Table Cells
    

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30. protocol NibLoadable: class {
    static var nibName: String { get }
    static var nib: UINib { get }
    }
    extension NibLoadable {
    static var nib: UINib {
    return UINib(nibName: nibName, bundle: NSBundle(forClass: self))
    }
    }
    

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31. protocol NibLoadable: class {
    static var nibName: String { get }
    static var nib: UINib { get }
    func createView(ofType _: View.Type) -> View
    }
    extension NibLoadable {
    static var nib: UINib {
    return UINib(nibName: nibName, bundle: NSBundle(forClass: self))
    }
    // Useful for custom view designed in xibs, eg: table header view, section headers, etc.
    static func createView(ofType _: View.Type)
    -> View {
    let nib = View.nib
    let nibContents = nib.instantiateWithOwner(nil, options: nil)
    assert(nibContents.count == 1, "\(nib) should hold only
    a single view, but found \(nibContents.count) items: \(nibContents)")
    return nibContents.first as! View
    }
    }
    

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32. class ChangePasswordCreateViewController: FormTableViewController {
    private lazy var tableHeaderView: FormTableHeaderView = {
    let headerView = createView(ofType: FormTableHeaderView.self)
    headerView.textLabel.text = NSLocalizedString("settings.change-
    password.create-new.header", comment: "Form table header text for new
    password creation.")
    Themer.themeDarkFormHeader(headerView)
    return headerView
    }()
    private func setupTableView() {
    // other stuff
    tableView.tableHeaderView = tableHeaderView
    }
    }
    

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33. Enum
    

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34. Humanize TableView
    Layout
    

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35. class StoreDetailsController: UITableViewController {
    private enum CellType: String {
    case Map = "MapCell"
    case Title = "TitleCell"
    case Address = "AddressCell"
    case Phone = "PhoneCell"
    case StoreHours = "StoreHoursCell"
    }
    private var cells: [CellType] = []
    private var store: Store!
    func configure(store: Store) {
    self.store = store
    cells = [.Map, .Title, .Address]
    if store.locationPhone != nil {
    cells.append(.Phone)
    }
    if store.storeHours != nil {
    cells.append(.StoreHours)
    }
    }
    }
    

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36. override func tableView(tableView: UITableView,
    cellForRowAtIndexPath indexPath: NSIndexPath) ->
    UITableViewCell {
    let cellType = cells[indexPath.row]
    let reuseIdentifier = cellType.rawValue
    let cell = tableView.dequeueReusableCellWithIdentifier(reuseIdentifier,
    forIndexPath: indexPath)
    switch cellType {
    case .Map:
    print("custom config")
    case .Title:
    print("custom config")
    case .Address:
    print("custom config")
    case .Phone:
    print("custom config")
    case .StoreHours:
    print("custom config")
    }
    return cell
    }
    

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37. enum UserProfileSections {
    case UsageDataSection
    case ContactInfoSection
    static let count = 2
    }
    enum UsageDataRows {
    case NumberOfTweetsRow
    case NumberOfFollowersRow
    static let count = 2
    }
    enum ContactInfoRows {
    case EmailRow
    case PhoneRow
    case PostalRow
    static let count = 3
    }
    

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38. Result
    

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39. enum WebServiceResult {
    case Success(String)
    case Error(Int)
    }
    let result = downloadWebContent()
    switch result {
    case .Success(let content):
    print("Success content: \(content)")
    case .Error(let errorCode):
    print("Error code: \(errorCode)")
    }
    

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40. UIImage
    

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41. extension UIImage {
    enum AssetIdentifier: String {
    case Location = "icon-location-small-gray"
    case Phone = "icon-phone"
    case Star = "icon-fav-location-off"
    case StarOn = "icon-fav-location-on"
    case StarGrey = "icon-fav-location-small-gray"
    case Time = "icon-time"
    case ChevronDown = "icon-chevron-down"
    case Error = "icon-error"
    }
    convenience init!(_ assetIdentifier: AssetIdentifier) {
    self.init(named: assetIdentifier.rawValue)
    }
    }
    let icon = UIImage(.Star)
    

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42. Dependency
    Injection
    Tell, Don’t Ask
    

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44. Not Easy :(
    

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45. extension DashboardViewController {
    func configure(toDoListStore: ToDoListStore, delegate:
    DashboardViewControllerDelegate) {
    self.toDoListStore = toDoListStore
    self.delegate = delegate
    }
    }
    

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46. Launch / Debug
    Menu
    

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48. struct MenuItem {
    let title: String
    let details: String?
    let runAction: ((navigation: UINavigationController) -> ())?
    }
    struct MenuSection {
    let title: String
    let items: [MenuItem]
    }
    struct Menu {
    let title: String
    let sections: [MenuSection]
    }
    

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49. extension Menu {
    static func appMemu() -> Menu {
    let uiColorDemo = MenuItem(title: "UIColor",
    details: "Building colors from hex values”,
    runAction: { (navigation) in
    let storyboard = UIStoryboard(name: "UIColorDemo", bundle: nil)
    let vc =
    storyboard.instantiateViewControllerWithIdentifier("UIColorDemoViewController")
    as! UIColorDemoViewController
    navigation.pushViewController(vc, animated: true)
    })
    let demos = MenuSection(title: "Demos", items: [uiColorDemo]);
    let menu = Menu(title: "Menu", sections: [demos])
    return menu
    }
    }
    class MenuViewController: UITableViewController { ... }
    

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50. Many DataSources
    

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56. Resources
    • Weather Demo, that illustrates some of the patterns
    discussed.

    https://github.com/zorn/WeatherDemo
    • Collection of source files, used to prep slides.

    https://github.com/zorn/CodePatternsScratchPad
    • https://www.bignerdranch.com/opensource/
    

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57. Learn More?
    

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60. https://vimeo.com/144116310
    

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61. Thank you.
    Michael Zornek
    zorn@bignerdranch.com
    @zorn
    

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