Lock in $30 Savings on PRO—Offer Ends Soon! ⏳

Enum Factories And Generic Data Sources

Enum Factories And Generic Data Sources

Presented at CocoaHeads Montreal on November 16th, 2017.

Olivier Collet

November 16, 2017
Tweet

More Decks by Olivier Collet

Other Decks in Programming

Transcript

  1. IT STARTS WITH A PAGED REQUEST I’ll spare you the

    details. The most important thing is this: struct Cursor { let page: Int let perPage: Int let parameters: [String: Any]? }
  2. LET’S MOVE TO THE STUFF THE DATA SOURCE • It

    uses generics to handle photos and collections • It uses a factory to generate cursors and requests protocol PagedDataSourceFactory { func initialCursor() -> Cursor func request(with cursor: Cursor) -> PagedRequest }
  3. SO WHAT ABOUT THE FACTORY? THAT’S WHERE IT GETS REALLY

    enum PhotosDataSourceFactory: PagedDataSourceFactory { case photos(order: GetPhotosRequest.Order) case trending case search(query: String) case collection(identifier: String, curated: Bool) }
  4. WHAT ABOUT THAT PROTOCOL? IT’S GETTING func initialCursor() -> PagedRequest.Cursor

    { switch self { case .photos(let order): return GetPhotosRequest.cursor(with: order, page: 1, perPage: 20) case .trending: return GetHomePhotosRequest.cursor(with: nil) case .search(let query): return SearchPhotosRequest.cursor(with: query, page: 1, perPage: 20) ... } func request(with cursor: PagedRequest.Cursor) -> PagedRequest { switch self { case .photos(let order): return GetPhotosRequest(orderBy: order, page: cursor.page, perPage: cursor.perPage) case .trending: return GetHomePhotosRequest(with: cursor) case .search(let query): return SearchPhotosRequest(with: query, page: cursor.page, perPage: cursor.perPage) ... }
  5. OK, BUT HOW TO USE THIS? The PhotosViewController uses a

    data source: var dataSource: PagedDataSource<Photo> Which is set as easily as this: photosViewController.dataSource = PhotosDataSourceFactory.search(query:”summer").dataSource