From Xojo Documentation
| This class is supported on Mobile.
Use ＃If...＃Endif with the Target... constants to ensure you only use this class where it is supported.
New in 2020r2
A layout that controls specific Screens depending on the type of device being used.
An iOSLayout allows you to specify how your app looks depending on the type of device being used. For example, on an iPhone you can have your app display a single Screen that contains a Table with a list of items. To do this, in the Navigator, select the iPhoneLayout then in the Inspector, set the Content property to the Screen you wish to be your default. The iPhoneLayout is already set in the App Inspector as the default screen to use for an iPhone.
On an iPad, you may instead want to have a split screen with a list of items on the left and detail information on the right. You can do this by setting the Content property for the iPadLayout to be Split and then setting the Screens for the Main and Detail sections. Refer to iOS Split Screen in the User Guide for more information.
You can have multiple iOSLayouts in your project and switch them at runtime. To do so you use the MobileApplication.CurrentLayout property and change the content like this:
iOS project types on iOS and iPadOS operating systems.