Dark appearance on iPhone not so dark

Last year MacOS got dark mode and this year iOS got the same, it's called light and dark appearance.

If you build a vanilla Qt app for an iPhone that's been set to dark appearance, native UI elements like QMessageBox gets the dark treatment but a QMainWindow does not, which means it difficult to see your cellular signal strength and the battery status on top.

Short term solution: add this key to the app's Info.plist:

<key>UIUserInterfaceStyle</key><string>Light</string>

This will make QMessageBoxes, signal strengths and battery status render like your iPhone is set to light appearance (i.e. opting out of dark appearance), more here: https://developer.apple.com/documentation/xcode/supporting_dark_mode_in_your_interface/choosing_a_specific_interface_style_for_your_ios_app?language=objc

A better is solution of course for Qt to support dark appearance (like it does very nicely on the Mac), but there seems to be no style plugin or similar infrastructure for iOS (as compared to MacOS) so this is most likely a long term thing?

Anyway: the reason I file this bug, please make Qt automagically add that key above to the Info.plist for a better UX on iOS 13 and later.