Iniziamo a vedere cosa ci offre il nuovo firmware 4.0 di iPhone.
Create un progetto come applicazione Window-based e chiamatela LocalPush.
Aggiungete l’stanza di bgTask in LocalPushAppDelegate:

@interface LocalPushAppDelegate : NSObject {
    UIWindow *window;
    UIBackgroundTaskIdentifier bgTask;
}

In LocalPushAppDelegate.m avremo:

//
//  LocalPushAppDelegate.m
//  LocalPush
//

@interface ToDoItem : NSObject  {
 NSInteger year;
 NSInteger month;
 NSInteger day;
 NSInteger hour;
 NSInteger minute;
 NSInteger second;
 NSString *eventName;
}

@property (nonatomic, readwrite) NSInteger year;
@property (nonatomic, readwrite) NSInteger month;
@property (nonatomic, readwrite) NSInteger day;
@property (nonatomic, readwrite) NSInteger hour;
@property (nonatomic, readwrite) NSInteger minute;
@property (nonatomic, readwrite) NSInteger second;
@property (nonatomic, copy) NSString *eventName;

@end

@implementation ToDoItem

@synthesize year, month, day, hour, minute, second, eventName;

@end

#import "LocalPushAppDelegate.h"

@implementation LocalPushAppDelegate

@synthesize window;

#define ToDoItemKey @"EVENTKEY1"
#define MessageTitleKey @"MSGKEY1"


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
    // avvio dell'applicazione
 
 UILocalNotification *localNotif = [launchOptions  objectForKey:UIApplicationLaunchOptionsLocalNotificationKey]; 
 
 if (localNotif) {
  NSString *itemName = [localNotif.userInfo objectForKey:ToDoItemKey]; 
  //  [viewController displayItem:itemName]; // custom method 
  application.applicationIconBadgeNumber = localNotif.applicationIconBadgeNumber-1; 
  NSLog(@"E' localNotif %@",itemName);
 }
 else {
  [[UIApplication sharedApplication] cancelAllLocalNotifications];
  NSDate *now = [NSDate date];
  NSLog(@"ora è %@",now);
  NSDate *scheduled = [now dateByAddingTimeInterval:120] ; 
  NSCalendar *calendar = [NSCalendar currentCalendar];

  unsigned int unitFlags = NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit;
  NSDateComponents *comp = [calendar components:unitFlags fromDate:scheduled];
  
  NSLog(@"schedulato %@",scheduled);
  
  ToDoItem *todoitem = [[ToDoItem alloc] init];
  
  todoitem.day = [comp day];
  todoitem.month = [comp month];
  todoitem.year = [comp year];
  todoitem.hour = [comp hour];
  todoitem.minute = [comp minute];
  todoitem.eventName = @"Testing Event";
  
  [self scheduleNotificationWithItem:todoitem interval:1];
  NSLog(@"scheduleNotificationWithItem");
 }
 [window makeKeyAndVisible];
 return YES;
}

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notif {
   NSLog(@"application: didReceiveLocalNotification:");
 NSString *itemName = [notif.userInfo objectForKey:ToDoItemKey];
 NSString *messageTitle = [notif.userInfo objectForKey:MessageTitleKey];
// [viewController displayItem:itemName]; // custom method 
 [self _showAlert:itemName withTitle:messageTitle];
 NSLog(@"Riceve Local Notification mentre l'app è ancora in esecuzione...");
 NSLog(@"notification corrente %@",notif);
 application.applicationIconBadgeNumber = notif.applicationIconBadgeNumber-1; 
 
}

- (void) _showAlert:(NSString*)pushmessage withTitle:(NSString*)title
{
 
 UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:title message:pushmessage delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
 [alertView show];
 if (alertView) { 
  [alertView release]; 
 }
}


- (void)scheduleNotificationWithItem:(ToDoItem *)item interval:(int)minutesBefore {
    NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
    NSDateComponents *dateComps = [[NSDateComponents alloc] init];
    [dateComps setDay:item.day];
    [dateComps setMonth:item.month];
    [dateComps setYear:item.year];
    [dateComps setHour:item.hour];
    [dateComps setMinute:item.minute];
    NSDate *itemDate = [calendar dateFromComponents:dateComps];
    [dateComps release];
 

    UILocalNotification *localNotif = [[UILocalNotification alloc] init];
    if (localNotif == nil)
        return;
    localNotif.fireDate = [itemDate dateByAddingTimeInterval:-(minutesBefore*60)];
  NSLog(@"Data %@",localNotif.fireDate);
    localNotif.timeZone = [NSTimeZone defaultTimeZone];
 
    localNotif.alertBody = [NSString stringWithFormat:NSLocalizedString(@"%@ in %i minuti.", nil),
       item.eventName, minutesBefore];
    localNotif.alertAction = NSLocalizedString(@"View Details", nil);
 
    localNotif.soundName = UILocalNotificationDefaultSoundName;
    localNotif.applicationIconBadgeNumber = 1;
//  NSDictionary *infoDict = [NSDictionary dictionaryWithObject:item.eventName forKey:ToDoItemKey];
  NSDictionary *infoDict = [NSDictionary dictionaryWithObjectsAndKeys:item.eventName,ToDoItemKey, @"Local Push ricevuto mentre è in esecuzione", MessageTitleKey, nil];
    localNotif.userInfo = infoDict;
 
    [[UIApplication sharedApplication] scheduleLocalNotification:localNotif];
  NSLog(@"scheduledLocalNotifications sono %@", [[UIApplication sharedApplication] scheduledLocalNotifications]);
    [localNotif release];
}

- (NSString *) checkForIncomingChat {
 return @"Soft!";
};

- (void)applicationDidEnterBackground:(UIApplication *)application {
    NSLog(@"L'applicazione entra in un stato di background.");
    // UIBackgroundTaskIdentifier bgTask istanza
    NSAssert(self->bgTask == UIInvalidBackgroundTask, nil);
 
    bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            [application endBackgroundTask:self->bgTask];
            self->bgTask = UIInvalidBackgroundTask;
        });
    }];
 
    dispatch_async(dispatch_get_main_queue(), ^{
        while ([application backgroundTimeRemaining] > 1.0) {
            NSString *friend = [self checkForIncomingChat];
            if (friend) {
                UILocalNotification *localNotif = [[UILocalNotification alloc] init];
                if (localNotif) {
                    localNotif.alertBody = [NSString stringWithFormat:
           NSLocalizedString(@"%@ ha un messaggio per te.", nil), friend];
                    localNotif.alertAction = NSLocalizedString(@"Read Msg", nil);
                    localNotif.soundName = @"alarmsound.caf";
                    localNotif.applicationIconBadgeNumber = 1;
      NSDictionary *infoDict = [NSDictionary dictionaryWithObjectsAndKeys:@"Tuo task in background",ToDoItemKey, @"Message from Soft!", MessageTitleKey, nil];
      localNotif.userInfo = infoDict;
                    [application presentLocalNotificationNow:localNotif];
                    [localNotif release];
                    friend = nil;
                    break;
                }
            }
        }
        [application endBackgroundTask:self->bgTask];
        self->bgTask = UIInvalidBackgroundTask;
    });
}

 
- (void)dealloc {
    [window release];
    [super dealloc];
}


@end