Update 10/09/19 @ 4:30 AM ET: YouTube has finally received proper dark theme syncing. Scroll to the bottom for more information. The article as published on September 18, 2019, is preserved as below.
In my opinion, the best new feature in Android 10 is the system-wide dark theme toggle. When I used to be big into custom ROMs and theming, I would slap a dark theme onto every app I possibly could. Now that Google has added a dark theme toggle to Android and is encouraging all developers to add their own dark themes, I no longer have to tinker with my phone so heavily. Google has led the effort to adopt dark themes in Android by rolling out updates for its entire app suite, but we've also seen third-party apps like Tasker and Reddit join in and add dark modes that respect Android 10's setting. Now, the latest beta version of the popular Nova Launcher app has added a new "System" theme that follows Android 10's setting, and we've spotted evidence that the YouTube app is about to add a similar feature.
System Theme in Nova Launcher
If you install the latest beta update (available from the official website or on Google Play), you'll see a new "System" theme in the Night Mode dropdown in Nova Settings. Enabling this setting will cause Nova to change between the light theme or dark theme automatically whenever you toggle the theme in Android 10. You can already automate Nova's dark theme based on a custom schedule or the Sunrise/Sunset schedule for your location, but thanks to the recent feature addition to Tasker you'll have much more control over it.
Unlike the dark mode in most other applications, Nova Launcher's dark mode is much more customizable. You can change the background color and toggle which parts of the launcher get themed, including the search bar, app drawer, drawer icon, or folders. A recent beta update even added support for toggling dark mode in the Google Discover feed.
Work-in-progress System Theme in YouTube
An APK teardown can often predict features that may arrive in a future update of an application, but it is possible that any of the features we mention here may not make it in a future release. This is because these features are currently unimplemented in the live build and may be pulled at any time by the developers in a future build.
Google widely rolled out a dark mode in the YouTube app last year, but you have to manually enable it in "General" settings. Strings in the latest 14.38.50 update reveal that the YouTube app will add a "system" theme setting that respects the dark mode preference in Android 10.
<string name="app_theme_appearance_dark">APPEARANCE_DARK</string>
<string name="app_theme_appearance_entry_dark">Dark theme</string>
<string name="app_theme_appearance_entry_light">Light theme</string>
<string name="app_theme_appearance_entry_system">Use device theme</string>
<string name="app_theme_appearance_light">APPEARANCE_LIGHT</string>
<string name="app_theme_appearance_summary">Choose your light or dark theme preference</string>
<string name="app_theme_appearance_system">APPEARANCE_SYSTEM</string>
<string name="app_theme_appearance_title">Appearance</string>
<string name="auto_switched_to_dark_by_device_theme">Dark theme is on to match your device theme</string>
<string name="auto_switched_to_light_by_device_theme">Light theme is on to match your device theme</string>
<string name="theme_not_match_with_system_theme">"New! Set YouTube's appearance to always match your device theme"</string>
I updated to the latest version on my Pixel 2 XL and OnePlus 7 Pro running Android 10, but the new preference did not show up on either device. I suspect it'll become available soon for some users via a server-side update before rolling out more widely in the coming weeks. We'll let you know when that happens.
Update: YouTube Dark Theme syncing is now rolling out
Dark theme syncing has begun rolling out for YouTube. This server-side change now allows YouTube to respect your system settings or you can choose to lock the app into either the light or dark theme depending on your preference. The change is rolling out server-side, but you would need to be on v14.38.50 or above to see the same. If you are looking for a higher version, you can download v14.40.52 from APKMirror.
Source: AndroidPolice