Checks whether multiple tasks are supported in iOS.

-(BOOL) application :( UIApplication *) application didfinishlaunchingwitexceptions :( NSDictionary *) launchOptions {

// Override point for customization after application launch.

RootViewController * rootController = [[RootViewControlleralloc] init];

RootController. title = @ "Root ";

NavController = [[UINavigationControlleralloc] initWithRootViewController: rootController];

[RootController release];

[Self. windowaddSubview: navController. view];

[Self. windowmakeKeyAndVisible];

// Check whether multiple tasks are supported.

UIDevice * device = [UIDevicecurrentDevice];

BOOL backgroundSupported = NO;

If ([devicerespondsToSelector: @ selector (isMultitaskingSupported)]) {

BackgroundSupported = device. multitaskingSupported;

NSLog (@ "background supported: % d", backgroundSupported );

}

Return YES;

}

If yes, 1 is printed; otherwise, 0 is printed.

In versions earlier than iOS4, the operating system does not support multitasking. Therefore, once an application leaves the foreground, it is terminated.

IOS4 and later versions support multitasking, but some devices that run the iOS4 version but do not support multitasking. A system that supports multiple tasks. When an application leaves the foreground, it will temporarily switch to the inactive status and then to the background status. If the event is not processed in the background, it will be suspended shortly after, that is, it will enter the suincluded state.

The reason for not exiting is to facilitate the next time you start the application quickly.

The reason for suspension is to reduce power consumption.