[iOS] Fixes root view's background color in bridgeless mode

[zhongwuzw]

Summary:

Fixes root view's background color in bridgeless mode, the top area has white background color when in dark mode.

Before:

After:

Changelog:

[IOS] [FIXED] - [iOS] Fixes the root view's background color in bridgeless mode

Test Plan:

Run RNTester and see the top area's background color.

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	17,151,003	+5
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	20,530,362	-11
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: b133bf6
Branch: main

[javache]

This doesn't seem like the right location for the fix. I'd imagine that the rootview actually covers the entire screen, and that the RNTester root should set the background color on the outmost container view, instead of something that's inside the SafeAreaView.

[javache]

Fix should be on the JS side.

[zhongwuzw]

@javache Emm, it's the default color for the root view, actually we do the same thing in non-bridgeless mode, please see:

- (UIView *)createRootViewWithBridge:(RCTBridge *)bridge
                          moduleName:(NSString *)moduleName
                           initProps:(NSDictionary *)initProps
{
  [self _logWarnIfCreateRootViewWithBridgeIsOverridden];
  BOOL enableFabric = self.fabricEnabled;
  UIView *rootView = RCTAppSetupDefaultRootView(bridge, moduleName, initProps, enableFabric);

  rootView.backgroundColor = [UIColor systemBackgroundColor];

  return rootView;
}

react-native/packages/react-native/Libraries/AppDelegate/RCTAppDelegate.mm

Line 169 in 25c5d1c

rootView.backgroundColor = [UIColor systemBackgroundColor];

[javache]

Ah, thanks for pointing that out. Still not a big fan for this, but let's do it for consistency.

[facebook-github-bot]

@javache has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@javache merged this pull request in 0bbc311.