Dealt with two problems back-to-back while working on a Flutter app. One was a UI-level issue – connecting components that were just shells with onTap: () {}. The other was a problem in Xcode 26.2 beta where the app itself wouldn’t install on the simulator due to extensions.

1. Connecting Non-Functional UI Components

A common situation during Flutter development: screens are all built, but buttons have onPressed: () {}, cards have onTap: () {}, and there’s no actual behavior.

Patterns by Type

Notification Bell Icon

A case where the UI exists but tapping isn’t even possible because there’s no GestureDetector.

// Before — just a Container
Container(
  child: Icon(Icons.notifications_outlined),
)

// After — wrapped with GestureDetector for routing
GestureDetector(
  onTap: () => context.push('/notifications'),
  child: Container(
    child: Icon(Icons.notifications_outlined),
  ),
)

“View All” Text Button

// Before
TextButton(onPressed: () {}, child: Text('View All'))

// After
TextButton(
  onPressed: () => context.push('/list-page'),
  child: Text('View All'),
)

Card Tap -> Bottom Sheet

A pattern where tapping a card shows a bottom sheet with detail info + action buttons.

GestureDetector(
  onTap: () => _showDetailSheet(context, item),
  child: Card(...),
)

void _showDetailSheet(BuildContext context, Item item) {
  showModalBottomSheet(
    context: context,
    backgroundColor: Colors.transparent,
    builder: (_) => Container(
      decoration: BoxDecoration(
        borderRadius: BorderRadius.vertical(top: Radius.circular(24)),
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Text(item.title),
          ElevatedButton(
            onPressed: () {
              Navigator.pop(context);
              context.push('/create');
            },
            child: Text('Create New'),
          ),
        ],
      ),
    ),
  );
}

Notification Page Structure

The app didn’t have a notification page at all, so I created one from scratch. It’s based on dummy data but structured so it can be replaced with API integration later.

class _NotificationItem {
  final String id;
  final _NotifType type;
  final String title;
  final String body;
  final String? tripId;   // Related target ID
  final DateTime time;
  bool isRead;
}

Swipe-to-delete with Dismissible, read status handling in BlocConsumer.

Dismissible(
  key: Key(notif.id),
  direction: DismissDirection.endToStart,
  onDismissed: (_) => _dismiss(notif.id),
  child: InkWell(
    onTap: () {
      _markRead(notif.id);
      if (notif.relatedId != null) {
        context.push('/detail/${notif.relatedId}');
      }
    },
    child: NotificationTile(notif: notif),
  ),
)

Fixing Existing Code Bugs

Three existing bugs discovered during the work:

1) Missing BlocConsumer listener

// Error: Required named parameter 'listener' must be provided
BlocConsumer<SomeBloc, SomeState>(
  builder: (context, state) { ... },
  // listener is missing
)

// Fix
BlocConsumer<SomeBloc, SomeState>(
  listener: (context, state) {},
  builder: (context, state) { ... },
)

2) Missing maybeMap orElse -> dynamic return

// Without orElse in maybeMap, return type becomes dynamic
// If shouldShow is dynamic, ternary operator causes compile error
final shouldShow = state.maybeMap(
  loaded: (data) => data.items.length >= 10,
  // no orElse → dynamic return
);

// Fix
final shouldShow = state.maybeMap(
  loaded: (data) => data.items.length >= 10,
  orElse: () => false,  // fixed to bool
);

3) Import path typo

// Wrong path (one extra directory depth)
import '../../bloc/some_bloc.dart';

// Correct path
import '../bloc/some_bloc.dart';

2. Xcode 26.2 Beta WidgetKit Extension Simulator Install Bug

Running flutter run on the simulator succeeds at the build stage but crashes during installation.

Unable to install Runner.app
Invalid placeholder attributes.
Failed to create app extension placeholder for PlugIns/SomeWidgetExtension.appex
Failed to create promise.

This occurred regardless of whether it was an iOS 18.x or iOS 26.x simulator.

Cause

In Xcode 26.2 beta, xcrun simctl install fails when creating placeholders for WidgetKit/ActivityKit extensions. “Failed to create promise” means the promise object used internally during App Extension registration in the simulator failed to be created.

This appears to be a regression from Xcode 26 being in beta, and there are no issues on real devices.

Workaround

Since the build itself succeeds, you can just remove the extension and install directly.

# 1. Build for simulator (extensions are included in the build)
flutter build ios --simulator --debug

# 2. Remove only the problematic extension
rm -rf build/ios/iphonesimulator/Runner.app/PlugIns/YourWidgetExtension.appex

# 3. Install directly with simctl
xcrun simctl install <DEVICE_UUID> build/ios/iphonesimulator/Runner.app

# 4. Launch
xcrun simctl launch <DEVICE_UUID> com.your.bundleid

Wrapping it in a Makefile makes it convenient:

SIM_DEVICE_ID = <device-uuid>
BUNDLE_ID     = com.your.app.bundleid
WIDGET_EXT    = YourWidgetExtension.appex

run-sim:
	flutter build ios --simulator --debug
	rm -rf build/ios/iphonesimulator/Runner.app/PlugIns/$(WIDGET_EXT)
	xcrun simctl install $(SIM_DEVICE_ID) build/ios/iphonesimulator/Runner.app
	xcrun simctl launch $(SIM_DEVICE_ID) $(BUNDLE_ID)

After that, a single make run-sim does everything.

Checking Booted Simulators

xcrun simctl list devices | grep Booted

The target simulator must be in Booted state. Installing on a Shutdown simulator gives the error Unable to lookup in current state: Shutdown.

# Boot simulator manually
xcrun simctl boot <DEVICE_UUID>
open -a Simulator

Summary

ProblemCauseSolution
No tap eventMissing GestureDetectorWrap + connect context.push()
View All empty functiononPressed: () {}Connect route or bottom sheet
BlocConsumer compile errorMissing listener parameterSpecify even an empty listener
maybeMap type errorMissing orElse -> dynamicAdd orElse: () => false
Simulator install failureXcode 26 beta bugRemove extension then simctl install

The Xcode 26 beta bug will be resolved naturally after the official release. Until then, proceed with development using the make run-sim workaround.