Apple is bringing multitasking to the tablet and bringing some significant new design and developer guidelines to app creators in the process. iPad Multitasking in iOS 9 includes three main features that developers and designers are going to need to know:
Three Modes Of iPad Multitasking In iOS 9
- Slide Over.
- Split View.
- Picture in Picture.
In the slide over mode (where one app overlays on another), the main app is called the primary app and will be on the left side of the screen. The right side app is called the secondary app. Slide over apps are dictated by a bar on the right side of the screen that functions as the secondary app trigger. Apple gives the example of a user looking at Apple Maps and then activating Safari to look up a store or a location.
Functions in much the same way as slide over, but instead of the secondary app on top of the primary app, both apps exist side by side.
Picture in Picture:
Allows for a video to float over the window of another app, giving the iPad the potential to display three apps at once. The best examples of picture in picture are for FaceTime calls for to watch a movie while looking at another app.
Xcode 7 gives developers an app template preconfigured to support Slide Over and Split View. Apple strongly suggests that all iPad apps support Slide Over and Split View unless there is a very strong reason not to, such as full device app like an arcade style video game. If your app does not support Slide Over and Split View, expect Apple’s App Store reviewers to ask why.
Note: Split View is currently only available in the iPad Air 2 and the iPad Pro upon its release. The iPad Mini 2/3 and the first iPad Air will support Slide Over and Picture in Picture, but not Split View.
The primary concern for iOS developers and designers is that Apple is changing the dimensions of their apps on the iPad in such a way as they will not fit or look right. Apple has been very careful to maintain similar aspect ratios for its screens over the last several iterations of iOS devices, in part to give developers a standard specification sheet to work from.
Apple notes that design of iPad apps is necessarily going to change. The device (screen) size is no longer the appropriate measure of an app’s available space. Rather, its “window” size (either as the primary app or the Split View or Slide Over app) is the designation for how much space an app can take up in iOS 9.
Similarly, Apple’s previous classes of device orientation for iOS will no longer apply for the iPad in iOS 9. In Split View, the user can change the window size of an app, leading to three five different size classes for apps. Apple notes these as “regular” and “compact” and includes horizontal and vertical orientations and various split screen options between them.
Creative developers and designers can try to figure out how their apps will work in the new windows sizes for the iPad. Apple’s best practices suggest letting Xcode and iOS 9 do the work for the developer through the Auto Layout feature (that was introduced in iOS 7 and updated over the years for new device and—now—window sizes).
Resource Management is top Priority
iPads are not PCs. For the most part, they are not built to run up to three apps on the screen at once. Perhaps the biggest concern that Apple has in the new iPad multitasking environment in iOS 9 is resource management.
For iPad multitasking purposes, Apple suggest that performance management come down to vigorous testing:
- Test the iOS 9 iPad app with Apple’s “Instrument” tool to make sure it is not leaking memory or growing memory consumption in an “unbounded fashion.”
- Use app state transition delegate methods that turn off much of the resources of an app when it is not actively in use (similar to the on-demand resources and app slicing).
- Test the apps on all the supported iOS iPad devices with another resource-intensive app (Apple suggests Maps set to Satellite view) as both the primary and secondary app.
If you are building iPad apps, the new multitasking rules are a little bit more than a strong suggestion from Apple in iOS 9. Developers should become familiar with the new system and techniques before the iPad Pro comes out later this year.