1 files changed, 42 insertions, 0 deletions
diff --git a/Hotline/Library/Utility/ObservableScrollView.swift b/Hotline/Library/Utility/ObservableScrollView.swift
new file mode 100644
index 0000000..05688f1
--- /dev/null
+++ b/Hotline/Library/Utility/ObservableScrollView.swift
@@ -0,0 +1,42 @@
+import SwiftUI
+
+struct ScrollViewOffsetPreferenceKey: PreferenceKey {
+  typealias Value = CGFloat
+  static var defaultValue = CGFloat.zero
+  static func reduce(value: inout Value, nextValue: () -> Value) {
+    value += nextValue()
+  }
+}
+
+struct ObservableScrollView<Content>: View where Content: View {
+  @Namespace var scrollSpace
+  @Binding var scrollOffset: CGFloat
+  let content: () -> Content
+
+  init(
+    scrollOffset: Binding<CGFloat>,
+    @ViewBuilder content: @escaping () -> Content
+  ) {
+    _scrollOffset = scrollOffset
+    self.content = content
+  }
+
+  var body: some View {
+    ScrollView {
+      content()
+        .background(
+          GeometryReader { geo in
+            let offset = -geo.frame(in: .named(scrollSpace)).minY
+            Color.clear
+              .preference(
+                key: ScrollViewOffsetPreferenceKey.self,
+                value: offset)
+          })
+
+    }
+    .coordinateSpace(name: scrollSpace)
+    .onPreferenceChange(ScrollViewOffsetPreferenceKey.self) { value in
+      scrollOffset = value
+    }
+  }
+}