How do i wrap a CupertinoApp in a Localizations widget so i can use Material widgets within it?

Question

I am using a CupertinoApp widget to wrap my app, while trying to use a Material TextFormField widget within it.

When I for example trigger the text selection mode (Double tap the text field), I am getting the following error (because it tries to open an overlay widget that requires material localizations):

Error message

No MaterialLocalizations found. OverlayEntry widgets require MaterialLocalizations to be provided by a Localizations widget ancestor.

Localizations are used to generate many different messages, labels,and abbreviations which are used by the material library.

To introduce a MaterialLocalizations, either use a MaterialApp at the root of your application to : include them automatically, or add a Localization widget with a MaterialLocalizations delegate.

---

The problem is that I cannot use a MaterialApp as I need to use Cupertino style navigation (nested navigators inside CupertinoTabBar/CupertinoTabView), so i need to use the Localization widget approach.

However the following code does not solve the problem:

void main() {
  runApp(
    Localizations(
      child: CupertinoApp(
        debugShowCheckedModeBanner: false,
        home: App(), // <-- Main Screen, a Cupertino Tab Scaffold with 3 CupertinoTabViews
      ),
      locale: Locale('en', 'US'),
      delegates: <LocalizationsDelegate>[

        // I assumed these were sufficient, but the runtime exception still persist.
        DefaultMaterialLocalizations.delegate,
        DefaultCupertinoLocalizations.delegate,
        DefaultWidgetsLocalizations.delegate,
      ],
    ),
  );
}

My question is then, what is the proper way to do this, is it not possible to use a Material widget within a CupertinoApp?

I/flutter ( 7631): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 7631): The following assertion was thrown building
I/flutter ( 7631): _OverlayEntry-[LabeledGlobalKey<_OverlayEntryState>#1e5c6](dirty, dependencies:
I/flutter ( 7631): [_LocalizationsScope-[GlobalKey#d1cfa]], state: _OverlayEntryState#ba2a3):
I/flutter ( 7631): No MaterialLocalizations found.
I/flutter ( 7631): _OverlayEntry widgets require MaterialLocalizations to be provided by a Localizations widget
I/flutter ( 7631): ancestor.
I/flutter ( 7631): Localizations are used to generate many different messages, labels,and abbreviations which are used
I/flutter ( 7631): by the material library. 
I/flutter ( 7631): To introduce a MaterialLocalizations, either use a  MaterialApp at the root of your application to
I/flutter ( 7631): include them automatically, or add a Localization widget with a MaterialLocalizations delegate.
I/flutter ( 7631): The specific widget that could not find a MaterialLocalizations ancestor was:
I/flutter ( 7631):   _OverlayEntry-[LabeledGlobalKey<_OverlayEntryState>#1e5c6]
I/flutter ( 7631): The ancestors of this widget were:
I/flutter ( 7631):   Stack(alignment: AlignmentDirectional.topStart, fit: expand, overflow: clip)
I/flutter ( 7631):   _Theatre
I/flutter ( 7631):   Overlay-[LabeledGlobalKey<OverlayState>#362c7]
I/flutter ( 7631):   _FocusScopeMarker
I/flutter ( 7631):   Semantics(container: false, properties: SemanticsProperties, label: null, value: null, hint: null,
I/flutter ( 7631):   hintOverrides: null)
I/flutter ( 7631):   FocusScope
I/flutter ( 7631):   AbsorbPointer(absorbing: false)
I/flutter ( 7631):   Listener(listeners: [down, up, cancel], behavior: deferToChild)
I/flutter ( 7631):   Navigator-[GlobalObjectKey<NavigatorState> _WidgetsAppState#2397a]
I/flutter ( 7631):   DefaultTextStyle(inherit: false, color: Color(0xff000000), family: .SF Pro Text, size: 17.0,
I/flutter ( 7631):   letterSpacing: -0.4, decoration: TextDecoration.none, softWrap: wrapping at box width, overflow:
I/flutter ( 7631):   clip)
I/flutter ( 7631):   Title(color: Color(0xff007aff))
I/flutter ( 7631):   Directionality(textDirection: ltr)
I/flutter ( 7631):   _LocalizationsScope-[GlobalKey#d1cfa]
I/flutter ( 7631):   Semantics(container: false, properties: SemanticsProperties, label: null, value: null, hint: null,
I/flutter ( 7631):   textDirection: ltr, hintOverrides: null)
I/flutter ( 7631):   Localizations(locale: en_US, delegates: [DefaultCupertinoLocalizations.delegate(en_US),
I/flutter ( 7631):   DefaultWidgetsLocalizations.delegate(en_US)])
I/flutter ( 7631):   MediaQuery(MediaQueryData(size: Size(411.4, 683.4), devicePixelRatio: 2.6, textScaleFactor: 1.0,
I/flutter ( 7631):   platformBrightness: Brightness.light, padding: EdgeInsets(0.0, 24.0, 0.0, 0.0), viewInsets:
I/flutter ( 7631):   EdgeInsets.zero, alwaysUse24HourFormat: false, accessibleNavigation: falsedisableAnimations:
I/flutter ( 7631):   falseinvertColors: falseboldText: false))
I/flutter ( 7631):   WidgetsApp-[GlobalObjectKey _CupertinoAppState#5df27]
I/flutter ( 7631):   IconTheme(IconThemeData#33904(color: Color(0xff007aff)))
I/flutter ( 7631):   _InheritedCupertinoTheme
I/flutter ( 7631):   CupertinoTheme
I/flutter ( 7631):   ScrollConfiguration(behavior: _AlwaysCupertinoScrollBehavior)
I/flutter ( 7631):   CupertinoApp
I/flutter ( 7631):   Directionality(textDirection: ltr)
I/flutter ( 7631):   _LocalizationsScope-[GlobalKey#dfb7d]
I/flutter ( 7631):   Semantics(container: false, properties: SemanticsProperties, label: null, value: null, hint: null,
I/flutter ( 7631):   textDirection: ltr, hintOverrides: null)
I/flutter ( 7631):   Localizations(locale: en_US, delegates: [DefaultMaterialLocalizations.delegate(en_US),
I/flutter ( 7631):   DefaultCupertinoLocalizations.delegate(en_US), DefaultWidgetsLocalizations.delegate(en_US)])
I/flutter ( 7631):   _InheritedModel<AppModel>
I/flutter ( 7631):   AnimatedBuilder(animation: Instance of 'AppModel')
I/flutter ( 7631):   ScopedModel<AppModel>
I/flutter ( 7631):   [root]
I/flutter ( 7631): 
I/flutter ( 7631): When the exception was thrown, this was the stack:
I/flutter ( 7631): #0      debugCheckHasMaterialLocalizations.<anonymous closure> (package:flutter/src/material/debug.dart:124:7)
I/flutter ( 7631): #1      debugCheckHasMaterialLocalizations (package:flutter/src/material/debug.dart:127:4)
I/flutter ( 7631): #2      _MaterialTextSelectionControls.buildToolbar (package:flutter/src/material/text_selection.dart:135:12)
// ....

Answer 1

You should not wrap CupertinoApp into a Localization.

CupertinoApp includes insert its own Localization widget, so whatever you added above CupertinoApp just gets overridden.

Instead, pass your delegates directly to localizationsDelegates of CupertinoApp:

CupertinoApp(
  localizationsDelegates: [
    DefaultMaterialLocalizations.delegate,
    DefaultCupertinoLocalizations.delegate,
    DefaultWidgetsLocalizations.delegate,
  ],
),

Answer 2

Just add to bottom GlobalCupertinoLocalizations.delegate where is GlobalMaterialLocalizations.delegate

Answer 3

Try these

localizationsDelegates: <LocalizationsDelegate<dynamic>>[
    GlobalWidgetsLocalizations.delegate,
    GlobalCupertinoLocalizations.delegate,
    GlobalMaterialLocalizations.delegate,
],

Full example

return MaterialApp(
    title: 'MyAppName',
    debugShowCheckedModeBanner: false,
    home: MyHomeScreen(),
    localizationsDelegates: <LocalizationsDelegate<dynamic>>[
        GlobalWidgetsLocalizations.delegate,
        GlobalCupertinoLocalizations.delegate,
        GlobalMaterialLocalizations.delegate,
    ],
    supportedLocales: <Locale>[
        const Locale('pt', 'BR'),
    ],
  );
}

It works with CupertinoApp too