iOS 5 Programming Cookbook

12.3. Receiving Local Notifications in the Background

Problem

You want to present an alert to your user even when your application is not running. You want to create this alert locally inside your application without using push notifications.

Solution

Instantiate an object of type UILocalNotification and schedule it using the scheduleLocalNotification: instance method of UIApplication:

- (BOOL) localNotificationWithMessage:(NSString *)paramMessage actionButtonTitle:(NSString *)paramActionButtonTitle launchImage:(NSString *)paramLaunchImage applicationBadge:(NSInteger)paramApplicationBadge secondsFromNow:(NSTimeInterval)paramSecondsFromNow userInfo:(NSDictionary *)paramUserInfo{ if ([paramMessage length] == 0){ return NO; } UILocalNotification *notification = [[UILocalNotification alloc] init]; notification.alertBody = paramMessage; notification.alertAction = paramActionButtonTitle; if ([paramActionButtonTitle length]> 0){ /* Make sure we have the action button for the user to press to open our application */ notification.hasAction = YES; } else { notification.hasAction = NO; } /* Here you have a chance to change the launch image of your application when the notification's action is viewed by the user */ notification.alertLaunchImage = paramLaunchImage; /* Change the badge number of the application once the notification is presented to the user. Even if the user dismisses the notification, the badge number of the application will change */ notification.applicationIconBadgeNumber = paramApplicationBadge; ...