Initialize locale from FlutterEngine (#17473)

* Initialize locale from FlutterEngine

shell/platform/darwin/ios/framework/Source/FlutterEngine.mm

@@ -122,6 +122,11 @@ NSString* const FlutterDefaultDartEntrypoint = nil;
                  name:UIApplicationWillResignActiveNotification
                object:nil];
 
+  [center addObserver:self
+             selector:@selector(onLocaleUpdated:)
+                 name:NSCurrentLocaleDidChangeNotification
+               object:nil];
+
   return self;
 }
 
@@ -494,6 +499,7 @@ NSString* const FlutterDefaultDartEntrypoint = nil;
                    << entrypoint.UTF8String;
   } else {
     [self setupChannels];
+    [self onLocaleUpdated:nil];
     if (!_platformViewsController) {
       _platformViewsController.reset(new flutter::FlutterPlatformViewsController());
     }
@@ -710,6 +716,48 @@ NSString* const FlutterDefaultDartEntrypoint = nil;
   _isGpuDisabled = value;
 }
 
+#pragma mark - Locale updates
+
+- (void)onLocaleUpdated:(NSNotification*)notification {
+  NSArray<NSString*>* preferredLocales = [NSLocale preferredLanguages];
+  NSMutableArray<NSString*>* data = [[NSMutableArray new] autorelease];
+
+  // Force prepend the [NSLocale currentLocale] to the front of the list
+  // to ensure we are including the full default locale. preferredLocales
+  // is not guaranteed to include anything beyond the languageCode.
+  NSLocale* currentLocale = [NSLocale currentLocale];
+  NSString* languageCode = [currentLocale objectForKey:NSLocaleLanguageCode];
+  NSString* countryCode = [currentLocale objectForKey:NSLocaleCountryCode];
+  NSString* scriptCode = [currentLocale objectForKey:NSLocaleScriptCode];
+  NSString* variantCode = [currentLocale objectForKey:NSLocaleVariantCode];
+  if (languageCode) {
+    [data addObject:languageCode];
+    [data addObject:(countryCode ? countryCode : @"")];
+    [data addObject:(scriptCode ? scriptCode : @"")];
+    [data addObject:(variantCode ? variantCode : @"")];
+  }
+
+  // Add any secondary locales/languages to the list.
+  for (NSString* localeID in preferredLocales) {
+    NSLocale* currentLocale = [[[NSLocale alloc] initWithLocaleIdentifier:localeID] autorelease];
+    NSString* languageCode = [currentLocale objectForKey:NSLocaleLanguageCode];
+    NSString* countryCode = [currentLocale objectForKey:NSLocaleCountryCode];
+    NSString* scriptCode = [currentLocale objectForKey:NSLocaleScriptCode];
+    NSString* variantCode = [currentLocale objectForKey:NSLocaleVariantCode];
+    if (!languageCode) {
+      continue;
+    }
+    [data addObject:languageCode];
+    [data addObject:(countryCode ? countryCode : @"")];
+    [data addObject:(scriptCode ? scriptCode : @"")];
+    [data addObject:(variantCode ? variantCode : @"")];
+  }
+  if (data.count == 0) {
+    return;
+  }
+  [self.localizationChannel invokeMethod:@"setLocale" arguments:data];
+}
+
 @end
 
 @implementation FlutterEngineRegistrar {

shell/platform/darwin/ios/framework/Source/FlutterViewController.mm

@@ -279,11 +279,6 @@ typedef enum UIAccessibilityContrast : NSInteger {
                  name:UIKeyboardWillHideNotification
                object:nil];
 
-  [center addObserver:self
-             selector:@selector(onLocaleUpdated:)
-                 name:NSCurrentLocaleDidChangeNotification
-               object:nil];
-
   [center addObserver:self
              selector:@selector(onAccessibilityStatusChanged:)
                  name:UIAccessibilityVoiceOverStatusChanged
@@ -595,7 +590,6 @@ static void sendFakeTouchEvent(FlutterEngine* engine,
 
 - (void)viewDidAppear:(BOOL)animated {
   TRACE_EVENT0("flutter", "viewDidAppear");
-  [self onLocaleUpdated:nil];
   [self onUserSettingsChanged:nil];
   [self onAccessibilityStatusChanged:nil];
   [[_engine.get() lifecycleChannel] sendMessage:@"AppLifecycleState.resumed"];
@@ -1054,48 +1048,6 @@ static flutter::PointerData::DeviceKind DeviceKindFromTouchType(UITouch* touch)
 #endif
 }
 
-#pragma mark - Locale updates
-
-- (void)onLocaleUpdated:(NSNotification*)notification {
-  NSArray<NSString*>* preferredLocales = [NSLocale preferredLanguages];
-  NSMutableArray<NSString*>* data = [[NSMutableArray new] autorelease];
-
-  // Force prepend the [NSLocale currentLocale] to the front of the list
-  // to ensure we are including the full default locale. preferredLocales
-  // is not guaranteed to include anything beyond the languageCode.
-  NSLocale* currentLocale = [NSLocale currentLocale];
-  NSString* languageCode = [currentLocale objectForKey:NSLocaleLanguageCode];
-  NSString* countryCode = [currentLocale objectForKey:NSLocaleCountryCode];
-  NSString* scriptCode = [currentLocale objectForKey:NSLocaleScriptCode];
-  NSString* variantCode = [currentLocale objectForKey:NSLocaleVariantCode];
-  if (languageCode) {
-    [data addObject:languageCode];
-    [data addObject:(countryCode ? countryCode : @"")];
-    [data addObject:(scriptCode ? scriptCode : @"")];
-    [data addObject:(variantCode ? variantCode : @"")];
-  }
-
-  // Add any secondary locales/languages to the list.
-  for (NSString* localeID in preferredLocales) {
-    NSLocale* currentLocale = [[[NSLocale alloc] initWithLocaleIdentifier:localeID] autorelease];
-    NSString* languageCode = [currentLocale objectForKey:NSLocaleLanguageCode];
-    NSString* countryCode = [currentLocale objectForKey:NSLocaleCountryCode];
-    NSString* scriptCode = [currentLocale objectForKey:NSLocaleScriptCode];
-    NSString* variantCode = [currentLocale objectForKey:NSLocaleVariantCode];
-    if (!languageCode) {
-      continue;
-    }
-    [data addObject:languageCode];
-    [data addObject:(countryCode ? countryCode : @"")];
-    [data addObject:(scriptCode ? scriptCode : @"")];
-    [data addObject:(variantCode ? variantCode : @"")];
-  }
-  if (data.count == 0) {
-    return;
-  }
-  [[_engine.get() localizationChannel] invokeMethod:@"setLocale" arguments:data];
-}
-
 #pragma mark - Set user settings
 
 - (void)traitCollectionDidChange:(UITraitCollection*)previousTraitCollection {

testing/scenario_app/lib/main.dart

@@ -43,6 +43,7 @@ Map<String, Scenario> _scenarios = <String, Scenario>{
 Scenario _currentScenario = _scenarios['animated_color_square'];
 
 void main() {
+  assert(window.locale != null);
   window
     ..onPlatformMessage = _handlePlatformMessage
     ..onBeginFrame = _onBeginFrame