Track presented feature form with preference

Author: dfeinzimer

Sources/ArcGISToolkit/Components/FeatureFormView/EmbeddedFeatureFormView.swift

@@ -16,9 +16,6 @@ import ArcGIS
 import SwiftUI
 
 struct EmbeddedFeatureFormView: View {
-    /// The environment value to access the closure to call when the presented feature form changes.
-    @Environment(\.formChangedAction) var formChangedAction
-    
     /// A Boolean value indicating whether the deprecated FeatureFormView initializer was used.
     @Environment(\.formDeprecatedInitializerWasUsed) var deprecatedInitializerWasUsed
 
@@ -86,9 +83,6 @@ struct EmbeddedFeatureFormView: View {
         .task {
             await embeddedFeatureFormViewModel.initialEvaluation()
         }
-        .onAppear {
-            formChangedAction?(embeddedFeatureFormViewModel.featureForm)
-        }
         .featureFormToolbar(embeddedFeatureFormViewModel.featureForm, isAForm: true)
     }
 }

Sources/ArcGISToolkit/Components/FeatureFormView/FeatureFormView+EnvironmentValues.swift

@@ -22,9 +22,6 @@ extension EnvironmentValues /* FeatureFormView */ {
     /// An error thrown from a call to `FeatureForm.finishEditing()`.
     @Entry var finishEditingError: Binding<(any Error)?> = .constant(nil)
 
-    /// The environment value to access the closure to call when the presented feature form changes.
-    @Entry var formChangedAction: ((FeatureForm) -> Void)?
-    
     /// A Boolean value indicating whether the deprecated FeatureFormView initializer was used.
     @Entry var formDeprecatedInitializerWasUsed = false
 

Sources/ArcGISToolkit/Components/FeatureFormView/FeatureFormView.swift

@@ -135,6 +135,10 @@ public struct FeatureFormView: View {
                         switch itemType {
                         case let .form(form):
                             EmbeddedFeatureFormView(featureForm: form)
+                                .preference(
+                                    key: PresentedFeatureFormPreferenceKey.self,
+                                    value: .init(featureForm: form)
+                                )
                         case let .utilityAssociationFilterResultView(result, embeddedFeatureFormViewModel):
                             UtilityAssociationsFilterResultView(
                                 embeddedFeatureFormViewModel: embeddedFeatureFormViewModel,
@@ -143,9 +147,10 @@ public struct FeatureFormView: View {
                             .featureFormToolbar(embeddedFeatureFormViewModel.featureForm)
                             .navigationBarTitleDisplayMode(.inline)
                             .navigationTitle(result.filter.title, subtitle: embeddedFeatureFormViewModel.title)
-                            .onAppear {
-                                formChangedAction(embeddedFeatureFormViewModel.featureForm)
-                            }
+                            .preference(
+                                key: PresentedFeatureFormPreferenceKey.self,
+                                value: .init(featureForm: embeddedFeatureFormViewModel.featureForm)
+                            )
                         case let .utilityAssociationGroupResultView(result, embeddedFeatureFormViewModel):
                             UtilityAssociationGroupResultView(
                                 embeddedFeatureFormViewModel: embeddedFeatureFormViewModel,
@@ -154,11 +159,12 @@ public struct FeatureFormView: View {
                             .featureFormToolbar(embeddedFeatureFormViewModel.featureForm)
                             .navigationBarTitleDisplayMode(.inline)
                             .navigationTitle(result.name, subtitle: embeddedFeatureFormViewModel.title)
-                            .onAppear {
-                                formChangedAction(embeddedFeatureFormViewModel.featureForm)
-                            }
                         }
                     }
+                    .preference(
+                        key: PresentedFeatureFormPreferenceKey.self,
+                        value: .init(featureForm: rootFeatureForm)
+                    )
             }
             // Alert for abandoning unsaved edits
             .alert(
@@ -261,7 +267,6 @@ public struct FeatureFormView: View {
             )
             .environment(\.editingButtonVisibility, editingButtonsVisibility)
             .environment(\.finishEditingError, $finishEditingError)
-            .environment(\.formChangedAction, formChangedAction)
             .environment(\.formDeprecatedInitializerWasUsed, deprecatedInitializerWasUsed)
             .environment(\.isPresented, isPresented)
             .environment(\.navigationIsDisabled, navigationIsDisabled)
@@ -270,6 +275,10 @@ public struct FeatureFormView: View {
             .environment(\.setAlertContinuation, setAlertContinuation)
             .environment(\.validationErrorVisibilityExternal, validationErrorVisibilityExternal)
             .environment(\.validationErrorVisibilityInternal, $validationErrorVisibilityInternal)
+            .onPreferenceChange(PresentedFeatureFormPreferenceKey.self) { wrappedFeatureForm in
+                guard let wrappedFeatureForm else { return }
+                formChangedAction(wrappedFeatureForm.featureForm)
+            }
         }
     }
 }

Sources/ArcGISToolkit/Components/FeatureFormView/PresentedFeatureFormPreferenceKey.swift

@@ -0,0 +1,37 @@
+// Copyright 2025 Esri
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import ArcGIS
+import SwiftUI
+
+/// A preference key that specifies the feature form currently presented in the `FeatureFormView` navigation stack.
+struct PresentedFeatureFormPreferenceKey: PreferenceKey {
+    /// A wrapper for making a feature form equatable.
+    struct EquatableFeatureForm: Equatable {
+        let featureForm: FeatureForm
+        
+        static func == (lhs: Self, rhs: Self) -> Bool {
+            lhs.featureForm === rhs.featureForm
+        }
+    }
+    
+    // MARK: PreferenceKey Conformance
+    
+    static let defaultValue: EquatableFeatureForm? = nil
+    
+    static func reduce(value: inout EquatableFeatureForm?, nextValue: () -> EquatableFeatureForm?) {
+        guard let nextValue = nextValue() else { return }
+        value = nextValue
+    }
+}