UIArrangementViewController

UIArrangementViewController takes two related views — a main one and a secondary one — and places them correctly for whatever pose the device is in, without you writing a layout branch per pose.

It is the UIKit half of a pair. The SwiftUI spelling is ArrangementView, and the two do the same job.

What it takes into account

You hand it the content; it reads the environment. The inputs are the size classes, the aspect ratio of the space it has, and any active division region — the strip the hinge occupies when the device is partially folded. That last one is why hand-rolled split layouts go wrong: they place a divider at 50% and the hinge is somewhere else.

Two styles

• Split — the two views sit side by side, or stacked, with the arrangement choosing which.
• Overlay — the secondary view floats above the main one. overlayArrangementZIndex controls which is on top.

The mistake worth naming

Reaching for the hinge angle to decide the layout. onHingeChange and UIHingeInteraction report an angle, and it is tempting to drive frames from it. Apple is explicit that the angle is for effects, not for layout — and an arrangement already handles the poses that angle was standing in for.

Not to be confused with

UISplitViewController, which is about a navigation hierarchy on a wide screen. An arrangement is about two pieces of content sharing a space that changes shape while the app is open.

Doing the work

This page describes the symbol. For what to change in an app that does not use it yet, and how urgent that is, see adopt ArrangementView for main-and-secondary layouts.