ios: adjust compose view background color to match top bar (#4456)

apps/ios/Shared/Views/Chat/ComposeMessage/ComposeView.swift

@@ -377,7 +377,7 @@ struct ComposeView: View {
                 }
             }
         }
-        .background(Color(uiColor: .tertiarySystemGroupedBackground))
+        .background(BlurView(style: .systemThinMaterial).ignoresSafeArea())
         .onChange(of: composeState.message) { msg in
             if composeState.linkPreviewAllowed {
                 if msg.count > 0 {
@@ -1114,6 +1114,17 @@ func parsedMsgHasSimplexLink(_ parsedMsg: [FormattedText]) -> Bool {
     parsedMsg.contains(where: { ft in ft.format?.isSimplexLink ?? false })
 }
 
+struct BlurView: UIViewRepresentable {
+    let style: UIBlurEffect.Style
+
+    func makeUIView(context: Context) -> UIVisualEffectView {
+        let view = UIVisualEffectView(effect: UIBlurEffect(style: style))
+        return view
+    }
+
+    func updateUIView(_ uiView: UIVisualEffectView, context: Context) {}
+}
+
 struct ComposeView_Previews: PreviewProvider {
     static var previews: some View {
         let chat = Chat(chatInfo: ChatInfo.sampleData.direct, chatItems: [])