Fix #148 by handling cancelled drag gestures (#149, thx @juhieta)

In addition to handling drag gesture changes & ending, also handle cancelled drag gesture. Fixes #148

Sources/BottomSheet/BottomSheetView/BottomSheetView+Gestures.swift

@@ -11,6 +11,8 @@ internal extension BottomSheetView {
     func dragGesture(with geometry: GeometryProxy) -> some Gesture {
         DragGesture()
             .onChanged { value in
+                self.lastDragValue = value
+
                 // Perform custom onChanged action
                 self.configuration.onDragChanged(value)
 
@@ -19,20 +21,10 @@ internal extension BottomSheetView {
                 // Dismiss the keyboard on drag
                 self.endEditing()
             }
-            .onEnded { value in
-                // Perform custom onEnded action
-                self.configuration.onDragEnded(value)
-
-                // Switch the position based on the translation and screen height
-                self.dragPositionSwitch(
-                    with: geometry,
-                    value: value
-                )
-
-                // Reset translation, because the dragging ended
-                self.translation = 0
-                // Dismiss the keyboard after drag
-                self.endEditing()
+            // Set isDragging flag to true while user is dragging
+            // The value is reset to false when dragging is stopped or cancelled
+            .updating($isDragging) { (value, gestureState, transaction) in
+                gestureState = true
             }
     }
 

Sources/BottomSheet/BottomSheetView/BottomSheetView.swift

@@ -8,7 +8,9 @@
 import SwiftUI
 
 internal struct BottomSheetView<HContent: View, MContent: View>: View {
-
+    @GestureState var isDragging: Bool = false
+    @State var lastDragValue: DragGesture.Value?
+
     // For iPhone landscape and iPad support
 #if !os(macOS)
     @Environment(\.horizontalSizeClass) var horizontalSizeClass: UserInterfaceSizeClass?
@@ -60,6 +62,26 @@ internal struct BottomSheetView<HContent: View, MContent: View>: View {
                     self.bottomSheet(with: geometry)
                 }
             }
+            // Handle drag ended or cancelled
+            // Drag cancellation can happen e.g. when user drags from bottom of the screen to show app switcher
+            .valueChanged(value: isDragging, onChange: { isDragging in
+                if lastDragValue != nil && !isDragging {
+                    // Perform custom onEnded action
+                    self.configuration.onDragEnded(lastDragValue!)
+
+                    // Switch the position based on the translation and screen height
+                    self.dragPositionSwitch(
+                        with: geometry,
+                        value: lastDragValue!
+                    )
+
+                    // Reset translation and last drag value, because the dragging ended
+                    self.translation = 0
+                    self.lastDragValue = nil
+                    // Dismiss the keyboard after drag
+                    self.endEditing()
+                }
+            })
             // Animate value changes
 #if !os(macOS)
             .animation(

Sources/BottomSheet/Helper/Extensions/ViewExtension.swift

@@ -0,0 +1,24 @@
+//
+//  ViewExtension.swift
+//
+//
+//  Created by Jukka Hietanen on 12.12.2023.
+//
+
+import Foundation
+
+import SwiftUI
+import Combine
+
+internal extension View {
+    /// A backwards compatible wrapper for iOS 14 `onChange`
+    @ViewBuilder func valueChanged<T: Equatable>(value: T, onChange: @escaping (T) -> Void) -> some View {
+        if #available(iOS 14.0, macOS 11.0, *) {
+            self.onChange(of: value, perform: onChange)
+        } else {
+            self.onReceive(Just(value)) { (value) in
+                onChange(value)
+            }
+        }
+    }
+}