Trait Collection specialised IB properties can't be changed in traitCollectionDidChange:

Number:rdar://42234720 Date Originated:16.07.2018
Status:closed - duplicate of 35713525 Resolved:
Product:iOS + SDK Product Version:iOS 12, Beta 3
Classification:Bug Reproducible:Always
When instantiating a view controller from a storyboard, `-[UIView(CALayerDelegate) layoutSublayersOfLayer:]` first calls `-[UIViewController traitCollectionDidChange:]` and then 
`-[UIView _processDidChangeRecursivelyFromOldTraits:toCurrentTraits:forceNotification:]`. The latter sets any properties that have been specialised for a specific trait collection in Interface Builder. Setting a different value in `traitCollectionDidChange:` or `viewWillAppear:` has no effect, leaving no good way of changing the initial value of such a property.

Steps to Reproduce:
- Set background color of a view to a Named Color
- Change the background color in `viewWillAppear:` and `traitCollectionDidChange:` to a different value, for example `[UIColor greenColor]`

Expected Results:
The view's background color is green

Actual Results:
The view's background color is the Named Color

iOS 12, Beta 3 (16A5318d)


Cannot migrate to named colors

still an issue in 2021 for xcode 11.4 and iOS 12.4

By michael.kropivka at Feb. 24, 2021, 8:40 a.m. (reply...)

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