UIViewReservedRegion

A reserved region is a rectangle of the display your content should not rely on being visible or touchable. On iPhone Duo there are two kinds, and they behave differently enough that treating them alike is a bug.

The two kinds

view.reservedRegions(kind: .division)    // the hinge, while partly folded
view.reservedRegions(kind: .occlusion)   // something covering the screen

Division is the hinge. It is active only while the device is partially folded and has zero width when the display is flat. That is the detail that catches people: a region that exists but measures nothing is easy to read as “no region” and hard-code around.

Occlusion is anything physically covering part of the display.

Asking about an inactive region

view.reservedRegions(kind: .division, options: .includeInactive)

Use this when you want to know where the division would fall before it does — to pre-position content rather than move it as the user folds.

What this is not

It is not a safe area. Safe areas describe the system’s own chrome; reserved regions describe the physical screen. A control inside the safe area can still land squarely on the fold.

The one exception

Apple’s guidance is to keep interactive elements out of these regions — with scrollable content as the stated exception. Text flowing across the fold is fine; a button sitting on it is not.

Doing the work

This page describes the symbol. For the task and how urgent it is, see keep content off the fold with division regions.