Tent posture
Stood up as a tent, with the inner display folded inwards, iPhone Duo keeps the app on the outer display, in landscape. iOS has no tent state. useHingeChange reports the angle the hinge is open at, around 81°, but its status lags behind the angle: a tent reached from closed reads closed, and one reached from open reads partiallyOpen. So don't look for a status. What makes a tent is the hinge being open while the app is on the outer display, which in landscape is a window with a compact height:
This follows Apple's guidance for iPhone Duo: there is no system pose, so infer one from the hinge angle, the orientation and the size class together, and keep the hinge for interactions and effects while the arrangement does the layout. Both thresholds are heuristics. Apple does not guarantee the precision or update rate of angle, so check the behavior on hardware.
Android has no tent posture either. A Pixel foldable hands over to its inner display as soon as it is open a little way, about 30° on the emulator, and from there WindowManager reports a half-open fold, which ArrangementView splits across. So the check above is true on Android only for a moment, with the cover display outwards.
Hiding headers and indicators
Usually in Tent posture, we want a fullscreen without distractions. Use the tent state to hide the navigation header, auto-hide the home indicator, and remove safe areas.
Example
The example app shows a bedside clock after the one Apple showed with iPhone Duo. The clock is the primary pane, so it's what shows where only one pane fits, and the alarm's settings are the secondary pane. In a tent, the clock fills the outer display in red, like StandBy at night. "Preview wake-up" plays the glow that comes before an alarm.
iOS
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iOS
Android
iOS
Android
iOS
Android
iOS
Android