March 2013
Intermediate to advanced
1000 pages
34h 51m
English
Content preview from Programming iOS 6, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Application Lifetime Events
As I explained in Chapter 6, your app’s one and only application object (a UIApplication instance, or on rare occasions a UIApplication subclass instance) is created for you as the shared application object by UIApplicationMain, along with its delegate; in the Xcode project templates, this is an instance of the AppDelegate class. As I’ve discussed earlier in this chapter, the application immediately starts reporting lifetime events through method calls to its delegate; subsequently, your other instances can also register to receive these same events as notifications. I can’t think of a better place in this book to describe these events, so I’m going to do so here and now.
What application lifetime events you can receive depends on whether or not your app participates in multitasking. In the old days, before iOS 4, there was no multitasking. If the user pressed the Home button while running your app, your app was terminated. The next time the user launched your app by tapping its icon, your app launched from scratch. Even under iOS 4 and later, your app can opt out of multitasking and behave like a pre–iOS 4 app, if you set the “Application does not run in background” key (UIApplicationExitsOnSuspend) in your Info.plist. For some apps, such as certain games, this might be a reasonable thing to do.
The suite of basic application lifetime events received by the app delegate in a nonmultitasking app is pretty simple:
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application:didFinishLaunchingWithOptions: ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.