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I have hard coded this Hour to help me fire the local notification at the top of each hour, but something is wrong. Though, I dunno if it's the way I'm testing it, my Xcode behaviour, or the code itself. Anyway, here is the code I made, have a look at it and please guide me to an easier or a better way to code such things. Thank You.

NSCalendar *calendar1 = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar1 components:(NSHourCalendarUnit |NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate:[NSDate date]];
hour = [components hour];
min =[components minute];
sec =[components second];
NSLog(@"hour is %i",hour);

NSLog(@"min is %i",min);

NSLog(@"sec is %i",sec);
if (hour < 24) {
 hour=hour+1;
 } else {
     hour=0;

And then..

[[UIApplication sharedApplication] cancelAllLocalNotifications];
NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar] ;
NSDateComponents *componentsForReferenceDate = [[NSDateComponents alloc] init];
[componentsForReferenceDate setHour:hour];
[componentsForReferenceDate setMinute:0];
[componentsForReferenceDate setSecond:0];

 NSDate *fireDateOfNotification = [calendar dateFromComponents: componentsForReferenceDate];

// Create the notification
user1949873
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2 Answers2

3

There are a few things to take on board here:

  • When asking for the date you don't need to ask for minutes and seconds as you scrap them anyway.
  • You should probably set a timeZone
  • When the hour is 23 you will add 1, which makes 24 which is not right

  • You don't need to create a new NSDateComponents object, you can just configure the one you have

    NSCalendar *calendar = [NSCalendar currentCalendar];
calendar.timeZone = [NSTimeZone timeZoneWithName:@"GMT"];

NSDateComponents *components = [calendar components:NSHourCalendarUnit fromDate:[NSDate date]];
components.hour   = (components.hour + 1) % 24;
components.minute = 0;
components.second = 0;

NSDate *fireDate = [calendar dateFromComponents:components];
NSLog(@"%@", fireDate);

The use of % for setting the hour prevents us going over 23

Paul.s
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  • Is there a difference between timeZone = [NSTimeZone localTimeZone]; and timeZone = [NSTimeZone defaultTimeZone]; ? and which is better to use? – user1949873 Jan 12 '13 at 01:59
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You aren't showing how you create the notification but the best way to repeat every hour would be to use a NSHourCalendarUnit repeat interval.

The local notification object, which is of type UILocalNotification has a property named repeatInterval which determines the repeat interval for the delivery of the notification.

notification.repeatInterval = NSHourCalendarUnit;

Your notification will repeat every hour, based on the time you specify, so you are setting everything correctly in the NSDate, i think just need to set the repeatInterval.

Bejmax
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