Fix tabbar hidding the composer in the demo app (#724)

Author: martinmitrevski

DemoAppSwiftUI/ChannelHeader/NewChatView.swift

@@ -92,6 +92,7 @@ struct NewChatView: View, KeyboardReadable {
                     viewFactory: DemoAppFactory.shared,
                     channelController: controller
                 )
+                .modifier(TabBarVisibilityModifier())
             } else {
                 Spacer()
             }
@@ -104,6 +105,19 @@ struct NewChatView: View, KeyboardReadable {
     }
 }
 
+struct TabBarVisibilityModifier: ViewModifier {
+    
+    func body(content: Content) -> some View {
+        if #available(iOS 18, *) {
+            content.toolbarVisibility(.hidden, for: .bottomBar)
+        } else if #available(iOS 16.0, *) {
+            content.toolbar(.hidden, for: .bottomBar)
+        } else {
+            content
+        }
+    }
+}
+
 struct SelectedUserView: View {
 
     @Injected(\.colors) var colors