Figured out a solution in my case
- Click the General Project Goals tab.
- Scroll down to the application icons and launch screens .
- Click the Use Asset Catalog button in the Image Launch Source section.
- At the invitation, select Migration - this will create the LaunchImage category under the .xcassets image installed (by default Images.xcassets in my case)
- Run the application - the problem with ifullscreen disappeared in my case

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