Is there a better way to compute the top of the hour code for repeat interval notification? [closed]

Question

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.

Closed 9 years ago.

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

Answer 1

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

Answer 2

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.