Raise deployment target to iOS 18 and modernize SwiftUI APIs

Adopt modern SwiftUI patterns now that the minimum target is iOS 18:
NavigationStack, .toolbar, .tint, new Tab API with sidebarAdaptable
style, and remove iOS 17 availability checks. Add Liquid Glass effect
support for iOS 26 in TimerView and fix an optional interpolation
warning in AppState.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Nextcloud Cookbook iOS Client/Views/MainView.swift

@@ -10,46 +10,40 @@ import SwiftUI
 struct MainView: View {
     @StateObject var appState = AppState()
     @StateObject var groceryList = GroceryList()
-    
+
     // Tab ViewModels
     @StateObject var recipeViewModel = RecipeTabView.ViewModel()
     @StateObject var searchViewModel = SearchTabView.ViewModel()
-    
+
+    @State private var selectedTab: Tab = .recipes
+
     enum Tab {
         case recipes, search, groceryList
     }
-    
+
     var body: some View {
-        TabView {
-            RecipeTabView()
-                .environmentObject(recipeViewModel)
-                .environmentObject(appState)
-                .environmentObject(groceryList)
-                .tabItem {
-                    Label("Recipes", systemImage: "book.closed.fill")
-                }
-                .tag(Tab.recipes)
-            
-            SearchTabView()
-                .environmentObject(searchViewModel)
-                .environmentObject(appState)
-                .environmentObject(groceryList)
-                .tabItem {
-                    Label("Search", systemImage: "magnifyingglass")
-                }
-                .tag(Tab.search)
-            
-            GroceryListTabView()
-                .environmentObject(groceryList)
-                .tabItem {
-                    if #available(iOS 17.0, *) {
-                        Label("Grocery List", systemImage: "storefront")
-                    } else {
-                        Label("Grocery List", systemImage: "heart.text.square")
-                    }
-                }
-                .tag(Tab.groceryList)
+        TabView(selection: $selectedTab) {
+            SwiftUI.Tab("Recipes", systemImage: "book.closed.fill", value: .recipes) {
+                RecipeTabView()
+                    .environmentObject(recipeViewModel)
+                    .environmentObject(appState)
+                    .environmentObject(groceryList)
+            }
+
+            SwiftUI.Tab("Search", systemImage: "magnifyingglass", value: .search, role: .search) {
+                SearchTabView()
+                    .environmentObject(searchViewModel)
+                    .environmentObject(appState)
+                    .environmentObject(groceryList)
+            }
+
+            SwiftUI.Tab("Grocery List", systemImage: "storefront", value: .groceryList) {
+                GroceryListTabView()
+                    .environmentObject(groceryList)
+            }
         }
+        .tabViewStyle(.sidebarAdaptable)
+        .modifier(TabBarMinimizeModifier())
         .task {
             recipeViewModel.presentLoadingIndicator = true
             await appState.getCategories()

Nextcloud Cookbook iOS Client/Views/Onboarding/OnboardingView.swift

@@ -148,7 +148,7 @@ struct BorderedLoginTextField: View {
             .autocorrectionDisabled()
             .textInputAutocapitalization(.never)
             .foregroundColor(color)
-            .accentColor(color)
+            .tint(color)
             .padding()
             .background(
                 RoundedRectangle(cornerRadius: 10)
@@ -170,7 +170,7 @@ struct LoginTextField: View {
             .autocorrectionDisabled()
             .textInputAutocapitalization(.never)
             .foregroundColor(color)
-            .accentColor(color)
+            .tint(color)
             .padding()
             .background(
                 RoundedRectangle(cornerRadius: 10)

Nextcloud Cookbook iOS Client/Views/Onboarding/V2LoginView.swift

@@ -187,12 +187,17 @@ struct WebViewSheet: View {
     @State var url: String
 
     var body: some View {
-        NavigationView {
+        NavigationStack {
             WebView(url: URL(string: url)!)
-                .navigationBarTitle(Text("Nextcloud Login"), displayMode: .inline)
-                .navigationBarItems(trailing: Button("Done") {
-                    dismiss()
-                })
+                .navigationTitle("Nextcloud Login")
+                .navigationBarTitleDisplayMode(.inline)
+                .toolbar {
+                    ToolbarItem(placement: .topBarTrailing) {
+                        Button("Done") {
+                            dismiss()
+                        }
+                    }
+                }
         }
     }
 }

Nextcloud Cookbook iOS Client/Views/Recipes/RecipeViewSections/RecipeGenericViews.swift

@@ -69,7 +69,7 @@ struct EditableListView: View {
     @State var axis: Axis = .vertical
     
     var body: some View {
-        NavigationView {
+        NavigationStack {
             ZStack {
                 List {
                     if items.isEmpty {
@@ -83,12 +83,12 @@ struct EditableListView: View {
                         .onDelete(perform: deleteItem)
                         .onMove(perform: moveItem)
                         .scrollDismissesKeyboard(.immediately)
-                        
+
                     }
                 }
                 VStack {
                     Spacer()
-                    
+
                     Button {
                         addItem()
                     } label: {
@@ -101,12 +101,15 @@ struct EditableListView: View {
                     .padding()
                 }
             }
-            .navigationBarTitle(title, displayMode: .inline)
-            .navigationBarItems(
-                trailing: Button(action: { isPresented = false }) {
-                    Text("Done")
+            .navigationTitle(title)
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button(action: { isPresented = false }) {
+                        Text("Done")
+                    }
                 }
-            )
+            }
             .environment(\.editMode, .constant(.active))
         }
     }

Nextcloud Cookbook iOS Client/Views/Recipes/RecipeViewSections/RecipeIngredientSection.swift

@@ -30,11 +30,7 @@ struct RecipeIngredientSection: View {
                         }
                     }
                 } label: {
-                    if #available(iOS 17.0, *) {
-                        Image(systemName: "storefront")
-                    } else {
-                        Image(systemName: "heart.text.square")
-                    }
+                    Image(systemName: "storefront")
                 }.disabled(viewModel.editMode)
                 
                 SecondaryLabel(text: LocalizedStringKey("Ingredients"))
@@ -111,14 +107,8 @@ fileprivate struct IngredientListItem: View {
     var body: some View {
         HStack(alignment: .top) {
             if groceryList.containsItem(at: recipeId, item: ingredient) {
-                if #available(iOS 17.0, *) {
-                    Image(systemName: "storefront")
-                        .foregroundStyle(Color.green)
-                } else {
-                    Image(systemName: "heart.text.square")
-                        .foregroundStyle(Color.green)
-                }
-                    
+                Image(systemName: "storefront")
+                    .foregroundStyle(Color.green)
             } else if isSelected {
                 Image(systemName: "checkmark.circle")
             } else {

Nextcloud Cookbook iOS Client/Views/Recipes/TimerView.swift

@@ -55,8 +55,13 @@ struct TimerView: View {
         .bold()
         .padding()
         .background {
-            RoundedRectangle(cornerRadius: 20)
-                .foregroundStyle(.ultraThickMaterial)
+            if #available(iOS 26, *) {
+                Color.clear
+                    .glassEffect(.regular, in: .rect(cornerRadius: 20))
+            } else {
+                RoundedRectangle(cornerRadius: 20)
+                    .foregroundStyle(.ultraThickMaterial)
+            }
         }
     }
 }

Nextcloud Cookbook iOS Client/Views/ReusableViews/LiquidGlassModifiers.swift

@@ -0,0 +1,28 @@
+//
+//  LiquidGlassModifiers.swift
+//  Nextcloud Cookbook iOS Client
+//
+//  Created by Vincent Meilinger on 14.02.26.
+//
+
+import SwiftUI
+
+struct TabBarMinimizeModifier: ViewModifier {
+    func body(content: Content) -> some View {
+        if #available(iOS 26, *) {
+            content.tabBarMinimizeBehavior(.onScrollDown)
+        } else {
+            content
+        }
+    }
+}
+
+struct BackgroundExtensionModifier: ViewModifier {
+    func body(content: Content) -> some View {
+        if #available(iOS 26, *) {
+            content.backgroundExtensionEffect()
+        } else {
+            content
+        }
+    }
+}

Nextcloud Cookbook iOS Client/Views/Tabs/RecipeTabView.swift

@@ -72,7 +72,7 @@ struct RecipeTabView: View {
                     )
                     .id(category.id) // Workaround: This is needed to update the detail view when the selection changes
                 }
-                
+
             }
         }
         .tint(.nextcloudBlue)