Merge pull request #111 from omnivore-app/feature/incremental-library-loading

Incremental Home Feed Loading [Apple]

apple/OmnivoreKit/Sources/Binders/Scenes/HomeFeedScene.swift

@@ -12,15 +12,17 @@ extension HomeFeedViewModel {
     }
 
     viewModel.bind(services: services)
-    viewModel.loadItems(dataService: services.dataService, searchQuery: nil)
+    viewModel.loadItems(dataService: services.dataService, searchQuery: nil, isRefresh: false)
     return viewModel
   }
 
   func bind(services: Services) {
     performActionSubject.sink { [weak self] action in
       switch action {
+      case let .refreshItems(query: query):
+        self?.loadItems(dataService: services.dataService, searchQuery: query, isRefresh: true)
       case let .loadItems(query):
-        self?.loadItems(dataService: services.dataService, searchQuery: query)
+        self?.loadItems(dataService: services.dataService, searchQuery: query, isRefresh: false)
       case let .archive(linkId):
         self?.setLinkArchived(dataService: services.dataService, linkId: linkId, archived: true)
       case let .unarchive(linkId):
@@ -39,7 +41,7 @@ extension HomeFeedViewModel {
     .store(in: &subscriptions)
   }
 
-  private func loadItems(dataService: DataService, searchQuery: String?) {
+  private func loadItems(dataService: DataService, searchQuery: String?, isRefresh: Bool) {
     // Clear offline highlights since we'll be populating new FeedItems with the correct highlights set
     dataService.clearHighlights()
 
@@ -59,10 +61,10 @@ extension HomeFeedViewModel {
     }
 
     dataService.libraryItemsPublisher(
-      limit: 100,
+      limit: 10,
       sortDescending: true,
       searchQuery: searchQuery,
-      cursor: nil
+      cursor: isRefresh ? nil : cursor
     )
     .sink(
       receiveCompletion: { [weak self] completion in
@@ -80,9 +82,10 @@ extension HomeFeedViewModel {
         if thisSearchIdx > 0, thisSearchIdx <= self?.receivedIdx ?? 0 {
           return
         }
-        self?.items = result.items
+        self?.items = isRefresh ? result.items : (self?.items ?? []) + result.items
         self?.isLoading = false
         self?.receivedIdx = thisSearchIdx
+        self?.cursor = result.cursor
         stopNetworkActivityIndicator()
       }
     )

apple/OmnivoreKit/Sources/Models/FeedItem.swift

@@ -2,9 +2,11 @@ import Foundation
 
 public struct HomeFeedData {
   public let items: [FeedItem]
+  public let cursor: String?
 
-  public init(items: [FeedItem]) {
+  public init(items: [FeedItem], cursor: String?) {
     self.items = items
+    self.cursor = cursor
   }
 }
 

apple/OmnivoreKit/Sources/Services/DataService/Queries/LibraryItemsQuery.swift

@@ -71,7 +71,10 @@ public extension DataService {
         articlesSuccess: .init {
           QueryResult.success(
             result: HomeFeedData(
-              items: try $0.edges(selection: articleEdgeSelection.list)
+              items: try $0.edges(selection: articleEdgeSelection.list),
+              cursor: try $0.pageInfo(selection: Selection.PageInfo {
+                try $0.endCursor()
+              })
             )
           )
         },

apple/OmnivoreKit/Sources/Views/PrimaryContainerViews/HomeFeedView.swift

@@ -10,6 +10,7 @@ public final class HomeFeedViewModel: ObservableObject {
   @Published public var items = [FeedItem]()
   @Published public var isLoading = false
   @Published public var showPushNotificationPrimer = false
+  public var cursor: String?
 
   // These are used to make sure we handle search result
   // responses in the right order
@@ -17,6 +18,7 @@ public final class HomeFeedViewModel: ObservableObject {
   public var receivedIdx = 0
 
   public enum Action {
+    case refreshItems(query: String)
     case loadItems(query: String)
     case archive(linkId: String)
     case unarchive(linkId: String)
@@ -31,15 +33,14 @@ public final class HomeFeedViewModel: ObservableObject {
     self.detailViewModelCreator = detailViewModelCreator
   }
 
-  func itemAppeared(item: FeedItem) {
+  func itemAppeared(item: FeedItem, searchQuery: String) {
     if isLoading { return }
     let itemIndex = items.firstIndex(where: { $0.id == item.id })
     let thresholdIndex = items.index(items.endIndex, offsetBy: -5)
 
     // Check if user has scrolled to the last five items in the list
-    if itemIndex == thresholdIndex {
-      print("load more items triggered")
-      //      performActionSubject.send(.loadItems)
+    if let itemIndex = itemIndex, itemIndex > thresholdIndex, items.count < thresholdIndex + 10 {
+      performActionSubject.send(.loadItems(query: searchQuery))
     }
   }
 
@@ -124,7 +125,7 @@ public struct HomeFeedView: View {
             .opacity(0)
             .buttonStyle(PlainButtonStyle())
             .onAppear {
-              viewModel.itemAppeared(item: item)
+              viewModel.itemAppeared(item: item, searchQuery: searchQuery)
             }
             FeedCard(item: item)
           }.contextMenu {
@@ -268,6 +269,6 @@ public struct HomeFeedView: View {
   }
 
   private func refresh() {
-    viewModel.performActionSubject.send(.loadItems(query: searchQuery))
+    viewModel.performActionSubject.send(.refreshItems(query: searchQuery))
   }
 }