Implement pull to refresh on iOS

Multiplatform/Shared/ErrorHandler.swift

@@ -14,16 +14,6 @@ struct ErrorHandler {
 
 	private static var log = OSLog(subsystem: Bundle.main.bundleIdentifier!, category: "Application")
 
-//	public static func present(_ viewController: UIViewController) -> (Error) -> () {
-//		return { [weak viewController] error in
-//			if UIApplication.shared.applicationState == .active {
-//				viewController?.presentError(error)
-//			} else {
-//				ErrorHandler.log(error)
-//			}
-//		}
-//	}
-		
 	public static func log(_ error: Error) {
 		os_log(.error, log: self.log, "%@", error.localizedDescription)
 	}

Multiplatform/Shared/Sidebar/SidebarItem.swift

@@ -17,7 +17,7 @@ public enum SidebarItemIdentifier: Hashable, Equatable {
 }
 
 public enum RepresentedType {
-	case webFeed, folder, pseudoFeed, account, unknown
+	case smartFeedController, webFeed, folder, pseudoFeed, account, unknown
 }
 
 struct SidebarItem: Identifiable {
@@ -43,6 +43,8 @@ struct SidebarItem: Identifiable {
 	
 	var representedType: RepresentedType {
 		switch type(of: represented) {
+		case is SmartFeedsController.Type:
+			return .smartFeedController
 		case is SmartFeed.Type:
 			return .pseudoFeed
 		case is UnreadFeed.Type:

Multiplatform/Shared/Sidebar/SidebarView.swift

@@ -17,6 +17,14 @@ struct SidebarView: View {
 	@EnvironmentObject private var sidebarModel: SidebarModel
 	@State var navigate = false
 
+	@State var refreshErrorMessage = ""
+	@State var showRefreshError: Bool = false
+
+	private let threshold: CGFloat = 80
+	@State private var previousScrollOffset: CGFloat = 0
+	@State private var scrollOffset: CGFloat = 0
+	@State var refreshing: Bool = false
+	
 	@ViewBuilder var body: some View {
 		#if os(macOS)
 		VStack {
@@ -50,10 +58,22 @@ struct SidebarView: View {
 			}
 		}
 		#else
-		List {
-			rows
+		ZStack(alignment: .top) {
+			List {
+				rows
+			}
+			.background(RefreshFixedView())
+			.navigationTitle(Text("Feeds"))
+			.onPreferenceChange(RefreshKeyTypes.PrefKey.self) { values in
+				refreshLogic(values: values)
+			}
+			if refreshing {
+				ProgressView().offset(y: -40)
+			}
+		}
+		.alert(isPresented: $showRefreshError) {
+			Alert(title: Text("Account Error"), message: Text(verbatim: refreshErrorMessage), dismissButton: .default(Text("OK")))
 		}
-		.navigationTitle(Text("Feeds"))
 		#endif
 //		.onAppear {
 //			expandedContainers.data = expandedContainerData
@@ -63,6 +83,63 @@ struct SidebarView: View {
 //		}
 	}
 	
+	func refreshLogic(values: [RefreshKeyTypes.PrefData]) {
+		DispatchQueue.main.async {
+			let movingBounds = values.first { $0.vType == .movingView }?.bounds ?? .zero
+			let fixedBounds = values.first { $0.vType == .fixedView }?.bounds ?? .zero
+			scrollOffset = movingBounds.minY - fixedBounds.minY
+
+			// Crossing the threshold on the way down, we start the refresh process
+			if !refreshing && (scrollOffset > threshold && previousScrollOffset <= threshold) {
+				refreshing = true
+				AccountManager.shared.refreshAll(errorHandler: handleRefreshError)
+			}
+
+			// Crossing the threshold on the way UP, we end the refresh
+			if refreshing && previousScrollOffset > threshold && scrollOffset <= threshold {
+				refreshing = false
+			}
+			
+			// Update last scroll offset
+			self.previousScrollOffset = self.scrollOffset
+		}
+	}
+	
+	func handleRefreshError(_ error: Error) {
+		refreshErrorMessage = error.localizedDescription
+		showRefreshError = true
+	}
+	
+	struct RefreshFixedView: View {
+		var body: some View {
+			GeometryReader { proxy in
+				Color.clear.preference(key: RefreshKeyTypes.PrefKey.self, value: [RefreshKeyTypes.PrefData(vType: .fixedView, bounds: proxy.frame(in: .global))])
+			}
+		}
+	}
+
+	struct RefreshKeyTypes {
+		enum ViewType: Int {
+			case movingView
+			case fixedView
+		}
+
+		struct PrefData: Equatable {
+			let vType: ViewType
+			let bounds: CGRect
+		}
+
+		struct PrefKey: PreferenceKey {
+			static var defaultValue: [PrefData] = []
+
+			static func reduce(value: inout [PrefData], nextValue: () -> [PrefData]) {
+				value.append(contentsOf: nextValue())
+			}
+
+			typealias Value = [PrefData]
+		}
+	}
+	
 	var rows: some View {
 		ForEach(sidebarModel.sidebarItems) { sidebarItem in
 			if let containerID = sidebarItem.containerID {
@@ -84,7 +161,14 @@ struct SidebarView: View {
 					#if os(macOS)
 					SidebarItemView(sidebarItem: sidebarItem).padding(.leading, 4)
 					#else
-					SidebarItemView(sidebarItem: sidebarItem)
+					if sidebarItem.representedType == .smartFeedController {
+						GeometryReader { proxy in
+							SidebarItemView(sidebarItem: sidebarItem)
+								.preference(key: RefreshKeyTypes.PrefKey.self, value: [RefreshKeyTypes.PrefData(vType: .movingView, bounds: proxy.frame(in: .global))])
+						}
+					} else {
+						SidebarItemView(sidebarItem: sidebarItem)
+					}
 					#endif
 				}
 			}

NetNewsWire.xcodeproj/project.pbxproj

@@ -3144,8 +3144,8 @@
 				51392D1A24AC19A000BE0D35 /* SidebarExpandedContainers.swift */,
 				51408B7D24A9EC6F0073CF4E /* SidebarItem.swift */,
 				51919FAE24AA8EFA00541E64 /* SidebarItemView.swift */,
-				51E499FC24A9137600B667CB /* SidebarModel.swift */,
 				5177470824B2F87600EB0F74 /* SidebarListStyleModifier.swift */,
+				51E499FC24A9137600B667CB /* SidebarModel.swift */,
 				17D5F17024B0BC6700375168 /* SidebarToolbarModel.swift */,
 				172199F024AB716900A31D04 /* SidebarToolbarModifier.swift */,
 				51919FA524AA64B000541E64 /* SidebarView.swift */,