Handling Interrupts in IOS app development - iphone

Question

I want to know how we can handle interrupts like incoming call, sms when the app is in foreground. I read the apple documentation and it says that the app will temporarily go into inactive state ie. 'applicationWillResignActive' function will be called. And things like Stopping timers , periodic tasks and running metadata queries should be performed and when it comes back to active state, again these tasks have to be disabled. What kind of tasks are they referring to when they say timers and periodic tasks. And how can we establish these coding wise. Any help will be appreciated. thanks

Answer 1

Yes, when receiving a temporary interruption the following method from UIApplication gets called [Apple's documentation]:
- (void)applicationWillResignActive:(UIApplication *)application
The tasks they are referring with timers and periodic tasks are these kind that are being executed periodically with a timer. For instance, you could have a timer running in the background to update the content of your view. Then, when application will resign active, is where you should stop that timer.
For instance, let's suppose that you are running a timer to perform a task every 10 seconds:
// AppDelegate.m
// When application becomes active the timer is started
- (void)applicationDidBecomeActive:(UIApplication *)application {
self.timer = [NSTimer scheduledTimerWithTimeInterval:10.0
target:self
selector:#selector(scheduledTask:)
userInfo:nil
repeats:YES];
}
// When the application will resign active the timer is stopped
- (void)applicationWillResignActive:(UIApplication *)application {
[self.timer invalidate];
self.timer = nil;
}
The scheduled task would be:
- (void)scheduledTask:(NSTimer *)timer {
// Up to you... for instance: web service call
}