add pull to refresh for ipad grid view

apple/OmnivoreKit/Sources/App/Views/Home/HomeFeedViewIOS.swift

@@ -329,9 +329,21 @@ import Views
           }
         }
         .padding()
-        .background(Color(.systemGroupedBackground))
+        .background(
+          GeometryReader {
+            Color(.systemGroupedBackground).preference(
+              key: ScrollViewOffsetPreferenceKey.self,
+              value: $0.frame(in: .global).origin.y
+            )
+          }
+        )
+        .onPreferenceChange(ScrollViewOffsetPreferenceKey.self) { offset in
+          if !viewModel.isLoading, abs(offset) > 240 {
+            viewModel.loadItems(dataService: dataService, searchQuery: searchQuery, isRefresh: true)
+          }
+        }
 
-        if viewModel.isLoading {
+        if viewModel.items.isEmpty, viewModel.isLoading {
           LoadingSection()
         }
       }
@@ -339,3 +351,11 @@ import Views
   }
 
 #endif
+
+struct ScrollViewOffsetPreferenceKey: PreferenceKey {
+  typealias Value = CGFloat
+  static var defaultValue = CGFloat.zero
+  static func reduce(value: inout Value, nextValue: () -> Value) {
+    value += nextValue()
+  }
+}