An app may receive only part of a display. Respond to the scene and container geometry and handle scene-activation failure rather than assuming another window is available.
Example 10 resizes a dashboard through narrow, medium, and expanded widths. Example 11 simulates the availability and error states of a presenter/audience experience.
The multiple-display canvas is a state-machine teaching fixture. Native iPhone Duo multi-scene and scene-accessory behavior requires Xcode 27.1 and DeviceHub verification.