Flutter shows black screen when launching iOS app - ios

Question

The problem: I get a black screen in my iOS Flutter app after a proper
build (XCode or VSCode or Android Studio), without errors. As soon as
it installs and launches the screen goes to black, with no other sign of life.
The app is generated (I can see the icon on the screen), but as soon I
start the app, it goes completely black.
Setup: (See Flutter doctor below) I´m using Flutter with Firebase
Database in iOS physical device (also in various Simulator types).
Important: The same code for Android is working properly, no black
screen, everything works fine!
I'm pretty sure everything is properly configured in my Firebase
project, I've been checking every detail and, as I say, when
launching to an Android device, everything works fine. For iOS the
file GoogleService-Info.plist is in its place. The configuration of the Signing in XCode also done, and no errors there.
Outputs.-
Flutter doctor -v
[✓] Flutter (Channel stable, v1.12.13+hotfix.5, on Mac OS X 10.15.2
19C57, locale es-ES)
• Flutter version 1.12.13+hotfix.5 at /Users/desarrollo/development/flutter
• Framework revision 27321ebbad (2 weeks ago), 2019-12-10 18:15:01 -0800
• Engine revision 2994f7e1e6
• Dart version 2.7.0
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
• Android SDK at /Users/desarrollo/Library/Android/sdk
• Android NDK location not configured (optional; useful for native
profiling support)
• Platform android-29, build-tools 29.0.2
• Java binary at: /Applications/Android
Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build
1.8.0_202-release-1483-b49-5587405)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 11.3)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 11.3, Build version 11C29
• CocoaPods version 1.8.4
[✓] Android Studio (version 3.5)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 42.1.1
• Dart plugin version 191.8593
• Java version OpenJDK Runtime Environment (build
1.8.0_202-release-1483-b49-5587405)
[✓] VS Code (version 1.41.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.7.1
[✓] Connected device (1 available)
• iPhone 11 Pro Max • C9503E12-9146-452B-93AE-E31DBEA1097E • ios •
com.apple.CoreSimulator.SimRuntime.iOS-13-3 (simulator)
• No issues found!
pubspec.yaml (assume correct tabulations):
name: tumeteo_app
description: A new Flutter project.
version: 1.0.0+1
environment:
sdk: ">=2.2.2 <3.0.0"
dependencies:
flutter:
sdk: flutter
firebase_core: ^0.4.3+1
firebase_storage: ^3.1.0
firebase_storage_image: ^0.4.0
cloud_firestore: ^0.13.0+1
firebase_auth: ^0.15.3
curved_navigation_bar: ^0.3.1
carousel_pro: ^1.0.0
firebase_messaging: ^6.0.9
rflutter_alert: ^1.0.3
shared_preferences: ^0.5.6
image_cropper: ^1.1.0
image_picker: ^0.6.2+1
cupertino_icons: ^0.1.2
dev_dependencies:
flutter_test:
sdk: flutter
flutter_launcher_icons: ^0.7.4
flutter_icons:
android: "launcher_icon"
ios: true
image_path: "assets/icon/icon3.png"
adaptative_icon_background: "assets/icon/icon3.png"
flutter:
uses-material-design: true
assets:
- assets/images/
fonts:
- family: PermanentMarker
fonts:
- asset: fonts/PermanentMarker-Regular.ttf
- family: BarlowCondensed
fonts:
- asset: fonts/BarlowCondensed-Regular.ttf
- family: Handlee
fonts:
- asset: fonts/Handlee-Regular.ttf
- family: PathwayGothicOne
fonts:
- asset: fonts/PathwayGothicOne-Regular.ttf
- family: RopaSans
fonts:
- asset: fonts/RopaSans-Regular.ttf
Output from XCode Building:
2019-12-27 11:02:51.658802+0100 Runner[11289:50522] -
<AppMeasurement>[I-ACS036002] Analytics screen reporting is enabled.
Call +[FIRAnalytics setScreenName:setScreenClass:] to set the screen
name or override the default screen class name. To disable screen
reporting, set the flag FirebaseScreenReportingEnabled to NO (boolean)
in the Info.plist
2019-12-27 11:02:51.981673+0100 Runner[11289:49976]
[VERBOSE-1:callback_cache.cc(132)] Could not parse callback cache,
aborting restore
2019-12-27 11:02:51.984084+0100 Runner[11289:49976] Configuring the
default Firebase app...
2019-12-27 11:02:51.997756+0100 Runner[11289:50520] 6.14.0 -
[Firebase/Core][I-COR000004] App with name __FIRAPP_DEFAULT does not
exist.
2019-12-27 11:02:52.088688+0100 Runner[11289:50521] 6.14.0 -
[Firebase/Analytics][I-ACS023007] Analytics v.60107000 started
2019-12-27 11:02:52.089771+0100 Runner[11289:50521] 6.14.0 -
[Firebase/Analytics][I-ACS023008] To enable debug logging set the
following application argument: -FIRAnalyticsDebugEnabled
2019-12-27 11:02:52.111059+0100 Runner[11289:49976] Configured the
default Firebase app __FIRAPP_DEFAULT.
2019-12-27 11:02:52.226945+0100 Runner[11289:50556] 6.14.0 -
[Firebase/Messaging][I-FCM001000] FIRMessaging Remote Notifications
proxy enabled, will swizzle remote notification receiver handlers. If
you'd prefer to manually integrate Firebase Messaging, add
"FirebaseAppDelegateProxyEnabled" to your Info.plist, and set it to
NO. Follow the instructions at:
https://firebase.google.com/docs/cloud-messaging/ios/client#method_swizzling_in_firebase_messaging
to ensure proper integration.
OUTPUT from VSCode:
Launching lib/main.dart on iPhone 11 Pro Max in debug mode...
Xcode build done. 570,6s
path: satisfied (Path is satisfied), interface: en0
[VERBOSE-1:callback_cache.cc(132)] Could not parse callback cache,
aborting restore
Configuring the default Firebase app...
path: satisfied (Path is satisfied), interface: en0
Configured the default Firebase app __FIRAPP_DEFAULT.
path: satisfied (Path is satisfied), interface: en0
https://firebase.google.com/docs/cloud-messaging/ios/client#method_swizzling_in_firebase_messaging
to ensure proper integration.

Answer 1

There's a message thrown from the app App with name __FIRAPP_DEFAULT does not exist. - this error commonly appears when Firebase isn't initialized correctly in the Flutter app. Import the packages in the Flutter app's main.dart and initialize Firebase
import 'package:firebase_core/firebase_core.dart';
import 'firebase_options.dart';
...
await Firebase.initializeApp(
options: DefaultFirebaseOptions.currentPlatform,
);
You can follow this guide for more details.