From Xojo Documentation
| This class is supported on Mobile (iOS).
Use ＃If...＃Endif with the Target... constants to ensure you only use this class where it is supported.
Used to embed UIViews created via declares into the Xojo control hierarchy.
Each iOSControl has an underlying UIView. The iOSUserControl class lets you hand the framework explicitly what you want it to use for the UIView.
In the CreateView event, you should create and configure whatever UIView you want. If the UIView's initializer requires a frame rectangle, pass in anything arbitrary (it will be placed correctly via auto layout). The UIView should be returned autoreleased and not just the result of alloc+init.
You cannot place an iOSUserControl (from the Library) directly on a layout. Instead you must subclass it, add code to the CreateView event handler and then drag the subclass onto the layout.