1227550 - Explore alternatives to UIAppearance for setting themes for the app

Status: RESOLVED WONTFIX

(Firefox for iOS :: Theme & Visual Design, defect)

Description

[Stephan Leroux [:sleroux]]

When applying private mode and normal themes for the browser, we're using the UIAppearance proxy to update the styles. A downside when using this API is that it's meant to be used early in the lifecycle [1] of the application to statically change appearances whereas we're using it to dynamically change the chrome theme while the app is used. We should investigate alternatives to dynamically theming the app since it's starting to cause bugs in implementing new features [2]

[1] From the Apple docs:

> iOS applies appearance changes when a view enters a window, 
> it doesn’t change the appearance of a view that’s already in a window.
> To change the appearance of a view that’s currently in a window, 
> remove the view from the view hierarchy and then put it back.

https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIAppearance_Protocol/index.html

[2] https://github.com/mozilla/firefox-ios/commit/5cf5dced4b019e8ffab6efdd196a5e518af83ac3

Comment 1

[Emily Toop (:fluffyemily)]

So, UIAppearance has been removed for this issue: https://bugzilla.mozilla.org/show_bug.cgi?id=1232017, but we still need a better styling option for introduction of Lightweight themes etc, so we should use this bug to investigate css-like (or other) alternatives.