iPhone Duo Split View not working usually comes down to how the phone is held or how the swipe is made. The phone has to be open and in landscape, and the swipe that places the second app needs a pause in the center before you drag.
Split View on iPhone Duo opens from a swipe or from a touch and hold on an app icon, and each route fails for a different reason. A second window of the same app also opens only in apps that support multiple windows.
iPhone Duo Split View Not Working Until the Phone Is Open and Sideways
Split View runs on the 7.6-inch inner display when the iPhone Duo is open in landscape. The inner display is the larger of the two, against 5.4 inches on the outer display.
- Open the iPhone Duo all the way.
- Turn it sideways so the inner display is wider than it is tall.
- Open the first app and try the gesture again.
Pause in the Center of the Swipe or Touch and Hold an App Icon
While using an app, swipe up from the bottom of the screen, pause in the center, then keep dragging the app to the left or right side. The app moves to that side and the Home Screen appears on the other half, where you tap the second app on the Home Screen or in App Library.
If the swipe keeps failing, touch and hold an app on the Home Screen or in App Library, tap Open in Split View, then pick the second app. This route skips the swipe and its pause. To move an app to the other side later, swipe up from the bottom of that app, pause in the center, then move it to the opposite side.
A Second Window Opens Only in Apps That Support Multiple Windows
Open an app that supports multiple windows in Split View, then tap its icon again on the Home Screen or in App Library, and a second window opens beside the first. Mail, Notes, Safari and Files support this, which suits two Safari tabs or an inbox next to a draft.
If an app will not open a second window, pair it with a different app instead. Older apps that cause iPhone Duo black bars can also look cramped beside a newer one, so swap that app out before blaming the phone.
Drag the Divider to an Edge to Unpair Apps or Show One Full Screen
Tapping the divider between two apps pairs them, and from then on opening either app opens the other as well. To unpair them, drag the divider all the way to the left or right edge of the screen.
The same edge drag shows one app in full screen, and swiping up from the middle of the screen goes to the Home Screen. When no apps will pair, check that both are open in Split View first, because the divider only exists once two apps share the screen.
The two apps always share the screen equally, so the divider cannot resize them and only moves to an edge. That is the fixed 50/50 layout on the 7.6-inch inner display.
Quit and Reopen the App or Restart the Phone When the Layout Stays Broken
If one app freezes or ignores the gesture, open the App Switcher, swipe right to find the app, then swipe up on it to quit it, and tap it on the Home Screen or in App Library to reopen it. If it is still unresponsive, restart the iPhone Duo.
If the phone will not turn off and back on, force restart it. Press and quickly release the volume button nearest the side button, then the other volume button, then hold the side button until the Apple logo appears. Afterward open Settings, tap General, tap Software Update and install any pending iOS update.
