You can add a UIImage to your launch screen. Once you've done that and set the constraints to fill the width and height then add an image to your asset catalogue.

On the properties of the image within the catalogue set the 'width class' and 'height class' to 'Any & compact'. Then you'll have spaces for images for Any and compact height (landscape) and Any and compact width (portrait). The just put your artwork in to the appropriate artwork placeholders and use that image on your storyboard.

I believe that will then choose the appropriate artwork for you depending on how the device is held when the app launches.

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