feat(hits): Inifinite Scroll components (#282)

Author: VladislavFitz

.github/workflows/pods.yml

@@ -6,30 +6,30 @@ jobs:
     steps:
      - uses: actions/checkout@v2
      - name: Select Xcode version
-       run: sudo xcode-select -s '/Applications/Xcode_13.4.app/Contents/Developer'
+       run: sudo xcode-select -s '/Applications/Xcode_14.2.app/Contents/Developer'
      - name: lint Insights
        run: pod lib lint --subspec="Insights" --allow-warnings
   lint-Core:
     runs-on: macos-12
     steps:
      - uses: actions/checkout@v2
      - name: Select Xcode version
-       run: sudo xcode-select -s '/Applications/Xcode_13.4.app/Contents/Developer'
+       run: sudo xcode-select -s '/Applications/Xcode_14.2.app/Contents/Developer'
      - name: lint Insights
        run: pod lib lint --subspec="Core" --allow-warnings
   lint-UI:
     runs-on: macos-12
     steps:
      - uses: actions/checkout@v2
      - name: Select Xcode version
-       run: sudo xcode-select -s '/Applications/Xcode_13.4.app/Contents/Developer'
+       run: sudo xcode-select -s '/Applications/Xcode_14.2.app/Contents/Developer'
      - name: lint Insights
        run: pod lib lint --subspec="UI" --allow-warnings
   lint-SwiftUI:
     runs-on: macos-12
     steps:
      - uses: actions/checkout@v2
      - name: Select Xcode version
-       run: sudo xcode-select -s '/Applications/Xcode_13.4.app/Contents/Developer'
+       run: sudo xcode-select -s '/Applications/Xcode_14.2.app/Contents/Developer'
      - name: lint Insights
        run: pod lib lint --subspec="SwiftUI" --allow-warnings

.github/workflows/swift.yml

@@ -4,7 +4,7 @@ on: [pull_request]
 
 jobs:
   test:
-    runs-on: macos-11
+    runs-on: macos-12
     env:
       ALGOLIA_APPLICATION_ID_1: ${{ secrets.ALGOLIA_APPLICATION_ID_1 }}
       ALGOLIA_ADMIN_KEY_1: ${{ secrets.ALGOLIA_ADMIN_KEY_1 }}
@@ -13,8 +13,8 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Select Xcode version
-        run: sudo xcode-select -s '/Applications/Xcode_13.2.app/Contents/Developer'
+        run: sudo xcode-select -s '/Applications/Xcode_14.2.app/Contents/Developer'
       - name: Build project
         run: swift build
       - name: Run tests
-        run: swift test
+        run: swift test

Examples/Showcase/Search/PaginationSingleIndex/SearchDemoSwiftUI.swift

@@ -33,8 +33,8 @@ struct SearchDemoSwiftUI: SwiftUIDemo, PreviewProvider {
   }
 
   struct ContentView: View {
+    @StateObject var hitsViewModel: InfiniteScrollViewModel<AlgoliaHitsPage<Hit<StoreItem>>>
     @ObservedObject var searchBoxController: SearchBoxObservableController
-    @ObservedObject var hitsController: HitsObservableController<Hit<StoreItem>>
     @ObservedObject var statsController: StatsTextObservableController
     @ObservedObject var loadingController: LoadingObservableController
 
@@ -47,15 +47,13 @@ struct SearchDemoSwiftUI: SwiftUIDemo, PreviewProvider {
             ProgressView()
           }
         }
-        .padding(.horizontal, 20)
-        HitsList(hitsController) { hit, _ in
-          ProductRow(storeItemHit: hit!)
+        .padding(.trailing, 20)
+        HitsList(hitsViewModel) { hit in
+          ProductRow(storeItemHit: hit)
             .padding()
             .frame(height: 100)
-          Divider()
         } noResults: {
           Text("No Results")
-            .frame(maxWidth: .infinity, maxHeight: .infinity)
         }
       }
       .searchable(text: $searchBoxController.query)
@@ -67,10 +65,11 @@ struct SearchDemoSwiftUI: SwiftUIDemo, PreviewProvider {
   }
 
   static func contentView(with controller: Controller) -> ContentView {
-    ContentView(searchBoxController: controller.searchBoxController,
-                hitsController: controller.hitsController,
-                statsController: controller.statsController,
-                loadingController: controller.loadingController)
+    let hitsViewModel = controller.demoController.searcher.infiniteScrollViewModel(of: Hit<StoreItem>.self)
+    return ContentView(hitsViewModel: hitsViewModel,
+                       searchBoxController: controller.searchBoxController,
+                       statsController: controller.statsController,
+                       loadingController: controller.loadingController)
   }
 
   static func viewController(searchTriggeringMode: SearchTriggeringMode) -> UIViewController {

InstantSearch.podspec

@@ -9,7 +9,7 @@ Pod::Spec.new do |s|
   s.author = { "Algolia" => "contact@algolia.com" }
   s.source = { :git => 'https://github.com/algolia/instantsearch-ios.git', :tag => s.version }
 
-  s.swift_version = "5.2"
+  s.swift_version = "5.8"
 
   s.default_subspec = 'UI'
 

Sources/InstantSearchCore/Hits/InfiniteScrolling/AlgoliaHitsPage+SearchResponse.swift

@@ -0,0 +1,57 @@
+//
+//  AlgoliaHitsPage+SearchResponse.swift
+//  
+//
+//  Created by Vladislav Fitc on 28/04/2023.
+//
+
+import Foundation
+
+extension AlgoliaHitsPage where Item: Decodable {
+
+  /// Initializes a new instance of `AlgoliaHitsPage` with the provided `SearchRespons`
+  ///
+  /// - Parameters:
+  ///     - searchResponse: An instance of `SearchResponse` object
+  ///
+  /// - Throws: `AlgoliaHitsPageSearchReponseError` instance
+  init(_ searchResponse: SearchResponse) throws {
+    guard let page = searchResponse.page else {
+      throw AlgoliaHitsPageSearchReponseError.missingPage
+    }
+    guard let nbPages = searchResponse.nbPages else {
+      throw AlgoliaHitsPageSearchReponseError.missingNbPages
+    }
+    let hits: [Item]
+    do {
+      hits = try searchResponse.extractHits()
+    } catch let error {
+      throw AlgoliaHitsPageSearchReponseError.hitsExtractionError(error)
+    }
+    self.init(page: page,
+              hits: hits,
+              hasPrevious: page > 0,
+              hasNext: page < nbPages-1)
+  }
+
+}
+
+/// Errors which may happen during construction of AlgoliaHitsPage with SearchResponse
+public enum AlgoliaHitsPageSearchReponseError: LocalizedError {
+
+  case missingPage
+  case missingNbPages
+  case hitsExtractionError(Error)
+
+  public var errorDescription: String? {
+    switch self {
+    case .missingPage:
+      return "nil `page` value in the search response"
+    case .missingNbPages:
+      return "nil `nbPages` value in the search response"
+    case let .hitsExtractionError(error):
+      return "hits decoding error from the search response: \(error.localizedDescription)"
+    }
+  }
+
+}

Sources/InstantSearchCore/Hits/InfiniteScrolling/AlgoliaHitsPage.swift

@@ -0,0 +1,76 @@
+//
+//  AlgoliaHitsPage.swift
+//  
+//
+//  Created by Vladislav Fitc on 27/04/2023.
+//
+
+import Foundation
+
+/// `AlgoliaHitsPage` is a generic struct that represents a paginated page of search results from
+/// the Algolia search engine, conforming to the `Page` protocol.
+///
+/// This struct requires the `Item` type and contains information about
+/// the current page, items, and navigation (previous and next pages) in the search results.
+///
+/// Usage:
+/// ```
+/// let algoliaHitsPage = AlgoliaHitsPage(page: 0,
+///                                       hits: [CustomItem(...)],
+///                                       hasPrevious: false,
+///                                       hasNext: true)
+/// ```
+///
+/// - Note: The `Item` type parameter represents the type of the items in the page and should conform to the `Decodable` protocol.
+public struct AlgoliaHitsPage<Item>: Page {
+
+  /// The current page number (zero-based).
+  public let page: Int
+
+  /// The list of items in the current page.
+  public let items: [Item]
+
+  /// A Boolean value indicating if there is a previous page in the search results.
+  public let hasPrevious: Bool
+
+  /// A Boolean value indicating if there is a next page in the search results.
+  public let hasNext: Bool
+
+  /// Initializes a new `AlgoliaHitsPage` object with the provided page number, items, and navigation flags.
+  ///
+  /// - Parameters:
+  ///   - page: The current page number (zero-based).
+  ///   - hits: The list of items in the current page.
+  ///   - hasPrevious: A Boolean value indicating if there is a previous page in the search results.
+  ///   - hasNext: A Boolean value indicating if there is a next page in the search results.
+  init(page: Int,
+       hits: [Item],
+       hasPrevious: Bool,
+       hasNext: Bool) {
+    self.page = page
+    self.items = hits
+    self.hasPrevious = hasPrevious
+    self.hasNext = hasNext
+  }
+
+  /// Determines if the left-hand side page is less than the right-hand side page.
+  ///
+  /// - Parameters:
+  ///   - lhs: The left-hand side `AlgoliaHitsPage`.
+  ///   - rhs: The right-hand side `AlgoliaHitsPage`.
+  /// - Returns: `true` if the left-hand side page is less than the right-hand side page, `false` otherwise.
+  public static func < (lhs: AlgoliaHitsPage, rhs: AlgoliaHitsPage) -> Bool {
+    lhs.page < rhs.page
+  }
+
+  /// Determines if the left-hand side page is equal to the right-hand side page.
+  ///
+  /// - Parameters:
+  ///   - lhs: The left-hand side `AlgoliaHitsPage`.
+  ///   - rhs: The right-hand side `AlgoliaHitsPage`.
+  /// - Returns: `true` if the left-hand side page is equal to the right-hand side page, `false` otherwise.
+  public static func == (lhs: AlgoliaHitsPage, rhs: AlgoliaHitsPage) -> Bool {
+    lhs.page == rhs.page
+  }
+
+}

Sources/InstantSearchCore/Hits/InfiniteScrolling/ConcurrentList.swift

@@ -0,0 +1,47 @@
+//
+//  PageStorage.swift
+//  
+//
+//  Created by Vladislav Fitc on 27/04/2023.
+//
+
+import Foundation
+
+/// `ConcurrentList` is a generic actor responsible for storing and managing items.
+/// It provides methods for appending, prepending, and clearing items.
+///
+/// Usage:
+/// ```
+/// let list = ConcurrentList<String>()
+/// list.append("some string")
+/// list.prepend("another string")
+/// list.clear()
+/// ```
+///
+/// - Note: The `Page` type parameter represents the type of the pages to be stored.
+@available(iOS 13.0.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+actor ConcurrentList<Item> {
+
+  /// An array containing the stored items.
+  var items: [Item] = []
+
+  /// Appends a given item to the end of the storage.
+  ///
+  /// - Parameter item: The `Item` to be appended.
+  func append(_ item: Item) {
+    items.append(item)
+  }
+
+  /// Prepends a given item to the beginning of the storage.
+  ///
+  /// - Parameter page: The `Item` to be prepended.
+  func prepend(_ item: Item) {
+    items.insert(item, at: 0)
+  }
+
+  /// Removes all the items from the storage.
+  func clear() {
+    items.removeAll()
+  }
+
+}

Sources/InstantSearchCore/Hits/InfiniteScrolling/HitsSearcher+InfiniteScrollViewModel.swift

@@ -0,0 +1,75 @@
+//
+//  HitsSearcher+PageSource.swift
+//  
+//
+//  Created by Vladislav Fitc on 27/04/2023.
+//
+
+import Foundation
+
+@available(iOS 13.0, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+public extension HitsSearcher {
+
+  /// Build `InfiniteScrollViewModel` with the current `HitsSearcher` instance as `PageSource`
+  func infiniteScrollViewModel<Item: Decodable>(of item: Item.Type) -> InfiniteScrollViewModel<AlgoliaHitsPage<Item>> {
+    let source = HitsSearcherPageSource<Item>(hitsSearcher: self)
+    let viewModel = InfiniteScrollViewModel(source: source)
+    onQueryChanged.subscribe(with: viewModel) { viewModel, _ in
+      Task {
+        await viewModel.reset()
+      }
+    }
+    return viewModel
+  }
+
+}
+
+/// Wrapper for `HitsSearcher` implementing the `PageSource protocol`
+@available(iOS 13, macOS 10.15, tvOS 13.0, watchOS 6.0, *)
+internal class HitsSearcherPageSource<Hit: Decodable>: PageSource {
+
+  typealias ItemsPage = AlgoliaHitsPage<Hit>
+
+  /// The wrapped `HitsSearcher` instance
+  let hitsSearcher: HitsSearcher
+
+  /// Initializes a new instance of `HitsSearcherPageSource` with a given `HitsSearcher` object.
+  ///
+  /// - Parameter hitsSearcher: The instance of `HitsSearcher`.
+  init(hitsSearcher: HitsSearcher) {
+    self.hitsSearcher = hitsSearcher
+  }
+
+  func fetchInitialPage() async throws -> ItemsPage {
+    hitsSearcher.request.query.page = 0
+    return try await getPage()
+  }
+
+  func fetchPage(before page: ItemsPage) async throws -> ItemsPage {
+    hitsSearcher.request.query.page = page.page-1
+    return try await getPage()
+  }
+
+  func fetchPage(after page: ItemsPage) async throws -> ItemsPage {
+    hitsSearcher.request.query.page = page.page+1
+    return try await getPage()
+  }
+
+  private func getPage() async throws -> ItemsPage {
+    try await withCheckedThrowingContinuation { continuation in
+      hitsSearcher.onResults.subscribeOnce(with: self) { _, response in
+        do {
+          let page = try AlgoliaHitsPage<Hit>(response)
+          continuation.resume(returning: page)
+        } catch let error {
+          continuation.resume(throwing: error)
+        }
+      }
+      hitsSearcher.onError.subscribeOnce(with: self) { _, error in
+        continuation.resume(throwing: error)
+      }
+      hitsSearcher.search()
+    }
+  }
+
+}