Fix Application always in light mode on initial load.

[filip131311]

Hi, I'm Filip from software mansion. This PR solves a problem I stumbled upon.

Summary:

On iOS, applications are always in light mode on initial load. Even if the device is turned to dark mode.

Cause of the problem:

The initial appearance is taken from RCTKeyWindow(), but at the time of initialization of RCTAppearance it does not exist yet.

Solution:

This PR moves repeats initialization of the appearance the first time getColorScheme() is called if it was not initialized properly before.

Changelog:

[IOS] [FIXED] - Fix dark mode on initial load.

Test Plan:

• Create new React native app with npx react-native@latest init AwesomeProjec
• Run the application on iphone using simulator
• turn on dark mode using cmd+shift+A
• close application and run it again

without changes:

The application will turn on in light mode despite the simulator being set to dark mode. When you reload the application it works as expected (is in dark mode)

with changes:

Works as expected

note:

any change to device ui settings will trigger a listener that will set appearance to correct state, so testing of this problem should happen in as isolated conditions as possible.

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[filip131311]

@cipolleschi I think you're right, I'll try going with your approach, Thank you!

[filip131311]

@cipolleschi Hello, I had a chance to look at the problem and unfortunately can not reproduce the CI failure.

1. Running test with ./scripts/objc-test.sh I get TEST SUCCEEDED:

Full log file is here: Run-RNTester-2024.04.30_20-20-55-+0200.xcresult.zip

2. Running tests with xcode I get:

so there is one fail but expected one, since I did not start web socket server by hand.

Furthermore, looking at my changes I don't agree that it is possible for anything to try and access _currentColorScheme before it is initialized, because the only other time in the entire codebase it is called is in appearanceChanged function in the same file, but if it was nil there it would also just be initialized.

Do you have any thoughts?

[cipolleschi]

hum.. tests are failing and before they weren't.. So there is something. I've tried to rerun the jobs, let's see if it is a fluke of the CI, although 4 jobs out of 4 testing it seems pretty systematic to me.

[cipolleschi]

I restarted the jobs but they are still failing. Let's try to rebase on top of main, but I think that there is something wrong here.

[cipolleschi]

/rebase - this comment automatically rebase on top of main

[filip131311]

@cipolleschi I am sorry it took me so long, but I added changes that fix the issue. It does not add a 3rd value as you suggested, because it could interfere with the rest of the code base, instead I added a static bool that indicates if the _currentColorSheme is Real or a default value.

What do you think?