Override traitCollection of UIView

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Created Jul ’21

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I am using a UIView with a nib as a template for a UIImage that I am generating, and I want to handle the output of the iPad in landscape differently than portrait. The best way I have figured I can do that is by setting up my landscape view for horizontal Regular, vertical Compact traits in the nib and assigning those traits before generating the image.

I have tried using the performAsCurrent method which successfully changes the UITraitCollection.current value but does not affect my UIView traitCollection property, and I have tried overriding the traitCollection getter in the UIView class which returns the error:

Class overrides the -traitCollection getter, which is not supported. If you're trying to override traits, you must use the appropriate API.

Is there a way to do this for a UIView that is never drawn to the screen?

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Answer 1

Frameworks Engineer OP

Apple

Jul ’21

Accepted Answer

The only supported APIs for changing the horizontal/vertical size class traits are the following:

UIPresentationController overrideTraitCollection https://developer.apple.com/documentation/uikit/uipresentationcontroller/1618335-overridetraitcollection

UIViewController setOverrideTraitCollection(_:forChild:) https://developer.apple.com/documentation/uikit/uiviewcontroller/1621406-setoverridetraitcollection

There isn't a way to change/override the size class traits of a UIView, so you will need to use one of the above APIs with the view inside of a view controller (and/or presentation), or modify your UIView's code to avoid using the size class traits directly and instead base its layout on your own properties which you control.

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