NSDate for "beginning of next hour"

Question

I'd like to make a countdown to the next full hour. It's pretty easy to countdown to a specific time, like:

NSDate *midnight = [NSDate dateWithNaturalLanguageString:@"midnight tomorrow"]; 

how do I define an NSDate for "the beginning of every hour"?

Thanks!

EDIT: This is what I have currently. Having trouble integrating the solutions in to my code. Any help would be greatly appreciated. :)

-(void)updateLabel {
NSDate *now = [NSDate date];

NSDate *midnight = [NSDate dateWithNaturalLanguageString:@"midnight tomorrow"]; 

//num of seconds between mid and now
NSTimeInterval timeInt = [midnight timeIntervalSinceDate:now];
int hour = (int) timeInt/3600;
int min = ((int) timeInt % 3600) / 60;
int sec = (int) timeInt % 60;
countdownLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hour, min,sec];
}  

Answer 1

Hi,

First of all I want to make clear that the method you are using is non-documented so it will possible cause rejection of ur app.

Now you can define the NSDate (if I understand ur question) like this:

NSDate *nextHr = [NSDate dateWithTimeIntervalSinceNow:3600];

or you can also do this

NSDate *nextHr = [[NSDate alloc] initWithTimeInterval:3600 sinceDate:RefDate];

Hope this helps.

Thanks,

Madhup

Answer 2

As +dateWithNaturalLanguageString is available on MacOS SDK only and your're targeting iPhone you'll need to make a method of your own. I think NSCalendar class can help you:

- (NSDate*) nextHourDate:(NSDate*)inDate{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comps = [calendar components: NSEraCalendarUnit|NSYearCalendarUnit| NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit fromDate: inDate];
    [comps setHour: [comps hour]+1]; // Here you may also need to check if it's the last hour of the day
    return [calendar dateFromComponents:comps];
}

I have not checked this code but it (at least this approach) must work.

Answer 3

You might want to check this out. Erica Sadun posted some extensions to NSDate.

http://github.com/erica/NSDate-Extensions