We've pointed out before that Split Screen is oddly tricky and a bit sludgy on OS X, but it's extremely useful
. It feels even more useful on iPad Pro, but it's still not the smoothest thing Apple has added. It has little limits we didn't expect, but we're really telling you this today because we were just in an Apple Store, and two of the staff were stumped when a customer asked them how you do Split Screen.
This was tested on an iPad Pro running iOS 9.2, but it also works the same way on the iPad Air 2. It's slower, but it's the same.
Just getting it started
You need to do this holding the iPad Pro in landscape rather than portrait. We happen to just prefer portrait, like we're holding a giant piece of paper, but Split Screen only works in landscape. Slide Over is fine: whatever you're reading or working on with the iPad Pro in portrait, you can slide over other apps to use them. It's not the same as Split Screen: you're using two apps, but the second one is like the iPhone version tacked on the side.
Let's start with how you do Slide Over, though, as sometimes you'll just want that, and it is always the route to the full Split Screen. Open any app on your iPad Pro, then place your finger on the right side of the device, actually touch the side bezel -- the black or white area surrounding the screen. Swipe in from the right -- you can't do this from the left -- and you immediately get the Slide Over pane. You may struggle if the app you're using already has something happen when you swipe from the sides, but in that case you'll get a little tab that you can press on to say it's iOS 9 swiping you want.
The main app you're using dims to show it's in the background, and most of the time the Slide Over pane shows you the latest app you had in it. Sometimes it will list all the available apps instead. This is surely the bit that Apple will change soon: right now, every app that can display in Slide Over is listed with its icon in an oversized border. You think the icons are too spaced out on the iPad Pro home screen? This is worse.
To pick an app to work in if none are open yet, just scroll up and down the list and tap on the one you want. If there is an app already open, and you want to pick a different one, look at the top. With one exception, every app you use in Slide Over has a stubby horizontal bar at the top. It'll be black, white, or gray, depending on the color of your app -- but when you see it, you can tap and tug on it to go to the long list of other apps.
The single exception, by the way, is if you're playing a video in Slide Over. We're not 100 per cent sure why you'd do this, but you can, and iOS 9 takes this bar away rather than interrupt your viewing experience. Tap on the video to bring up the controls, and it still doesn't show the bar: you have to tap Done, and go back to the list of videos first.
Go further, literally
We've become rather addicted to Slide Over on our iPad Airs, but rarely use it on iPad Pro because it's just so much handier and really so much easier to go further. When you're swiping in from the right and Slide Over appears, you can keep going, keep swiping.
As fast as the iPad Pro is, it can't animate windows shrinking and growing, so the display changes to a brightly colored mosaic image with the app icons in the center, and a bar between the two sides. Drag your finger across to roughly the center of the screen and let go. Actually, drag where you like: for all that you can move the dividing line between the apps to just about any part of the screen, it doesn't matter. Anything up to about a fifth of the way across gets you Slide Over; anything more gets you Split Screen, with the two apps taking up exactly half of the screen each.
You can only do this dragging when you have two apps open: if you have an app on the left, and the Slide Over-like list of apps on the other, you can't drag. Pick an app, any app, from the list and when it's opened, then you can drag. That second app, the one on the right of the screen, gets the same bar at the top that Slide Over ones do, and that's where you can tug down and change apps.
The app on the left has no bar, and can't be dragged away, can't be changed to another app. You do quickly get used to this: you get used to automatically regarding the left app as your primary one. However, when you first want to change it, it's not obvious what you have to do.
So let us tell you
If you have two apps open in Split Screen, and you want to change the one on the left, press the Home button. It takes you back to the iPad Pro's home screen, it takes you completely out of both apps, and you will think you've switched off Split Screen.
However, tap to launch any app you like: that will open, and it will open up back in Split Screen. The new app will be in the primary left slot and whatever you had open on the right will be back there exactly the way it was. It's important to note that not all apps yet support Split Screen, but all the ones on the iPad that are made by Apple do, and many third-party ones as well. So if it doesn't work for you at first, pick another app and try again.
-- William Gallagher (@WGallagher