I'm trying to sethours in NSDateComponents, I wrote the following code
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dateComps = [[NSDateComponents alloc] init];
[dateComps setDay:intDay];
[dateComps setMonth:intMonth];
[dateComps setYear:intYear];
[dateComps setHour:intHoures];
[dateComps setMinute:intMinutes];
NSDate *itemDate;
itemDate = [calendar dateFromComponents:dateComps];
NSLog(#"reminder date: %#", itemDate);
but when I set the hours as 13, it sets it as 11. I want hours in 24 style. Anyone can help me in this issue?
Thanks in Advance.
Time difference in the hours indicate that you might have problem with time zone, you could try to set the timezone for the date, I know NSDateFormatter has timeZone Property,I doubt if NSDateComponents have timeZone property. However you could set the timeZone for calendar
[calendar setTimeZone:[NSTimeZone timeZoneWithName:#"GMT"]];
Related
My iPhone app downloads an exchange rate from a website. It also downloads the time that the rate was last updated in EST. In my app, I want to compare that time to the [NSDate date].
Basically, I want to compare the downloaded time to the current EST using NSTimeInterval to calculate the difference.
I have looked on this site and read through the docs and am uncertain on how to achieve this. As far as I can understand, NSDate is without time zone. It is GMT. So I want to convert that to EST or convert my date to GMT and compare the two.
This is how I convert my downloaded data to a date:
NSDateComponents *dateComps = [[NSDateComponents alloc] init];
[dateComps setHour:hour];
[dateComps setMinute:minute];
[dateComps setDay:day];
[dateComps setMonth:month];
[dateComps setYear:year];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
self.lastUpdatedExchangeRateDate = [calendar dateFromComponents:dateComps];
I appreciate your input on the best way to go about this.
You should set the NSDateComponents' timeZone too:
dateComps.timeZone = [NSTimeZone timeZoneWithAbbreviation:#"EST"];
It's important to create the NSDate with the correct timezone, because it represents a second in time, and have no awareness of timezones.
Is there a way to subtract the current date by 5. say if today is 2008-12-9 i need to get the date 5 days back. If we output this, the date should display as 2008-12-4.
How can i code this programatically? or a tutorial that would help
Always use NSCalendar and NSDateComponents for date calculations. This will take into account oddities like leap years with 29 days in February, leap seconds and daylight saving changes.
NSDate *date = [NSDate date]; // Using current date here
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [[NSDateComponents alloc] init];
components.day = - 5; // Find date for 5 days ago
NSDate *newDate = [calendar dateByAddingComponents:components toDate:date options:0];
Use NSDateComponents
NSDate *today = [NSDate date];
NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDateComponents *offsetComponents = [[[NSDateComponents alloc] init] autorelease];
[offsetComponents setDays:-5];
NSDate *fiveDaysAgo = [gregorian dateByAddingComponents:offsetComponents toDate:today options:0];
to convert it to a string with the preferred format, use NSDateFormatter
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:#"yyyy-MM-dd"];
NSString *formattedDateString = [dateFormatter stringFromDate:fiveDaysAgo];
This is the brute-force way:
Sustract 5 from DAY.
If DAY < 0, add number of days of the previous month and sustract 1 from MONTH.
If MONTH < 0, add number of month of a year and sustract 1 from YEAR.
The advantage of the brute-force approach is that it will work with every language.
#define SOME_HOUR -24*5
NSDate *today = [NSDate date];
NSDate *someDay = [NSDate dateWithTimeInterval:60*60*SOME_HOUR sinceDate:today];
I think this is just a minor problem. After searching for some time I still can't figure it out. Hopefully you can. :-)
I want to get a full timestamp of today, passing own hours and minutes.
My approach was the following(dateStr is #"11:30" for example):
NSDateFormatter *myFormatter = [[[NSDateFormatter alloc] init] autorelease];
[myFormatter setTimeZone:[NSTimeZone systemTimeZone]];
[myFormatter setDateFormat:#"HH:mm"];
NSDate *tmpDate = [myFormatter dateFromString:dateStr];
[myFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss ZZZ"];
...???
So now I get
1970-01-01 11:30:00 +0000
What do I habe to do to apply the dateStyle to my NSDate and get the correct date of today?
I know that I can use [NSDate date] to get the actual date but what can I do to "manipulate" only minutes and hours?
Would be great to get some help from you guys :)
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorian components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit fromDate:[NSDate date]];
[components setHour:hour];
[components setMinute:minute];
NSDate *date = [gregorian dateFromComponents:components];
[gregorian release];
I want to set date and time two days after my current date and time.How i set it using NSDate and dateformatter. I want compare date after two days, it was perviously set or not.
I write code now for it,
NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
NSDate *pickerDate = [self.datePicker date];
NSDateComponents *dateComponents = [calendar components:( NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit )
fromDate:pickerDate];
NSDateComponents *timeComponents = [calendar components:( NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit )
fromDate:pickerDate];
NSDateComponents *dateComps = [[NSDateComponents alloc] init];
[dateComps setDay:[dateComponents day]];
[dateComps setMonth:[dateComponents month]];
[dateComps setYear:[dateComponents year]];
[dateComps setHour:[timeComponents hour]];
[dateComps setMinute:[timeComponents minute]];
[dateComps setSecond:00];
NSDate *itemDate = [calendar dateFromComponents:dateComps];
[dateComps release];
appDelegate.setTimerByUser = [itemDate retain];
How i compare it with current time and date?
Thanks
Look in NSDate.h and read Apple's docs for the -compare function on NSDates.
You can do for example:
NSDate *now = [NSDate date];
NSDate *future = [now dateByAddingTimeInterval: 2 * 24 * 60 * 60]; // add two days
if ( [now compare: future] == NSOrderedAscending ) {
// now is earlier than future so we will always get here
} else {
// never reached but illustrates how you might use compare
}
I think you need NSDateComponents. You can use this class to get year, month, day, and other attributes about date and time.
NSDate * now = [NSDate date];
NSDate * twoDaysFromNow = [now dateByAddingTimeInterval:(2 * 24* 60 * 60)];
You can compare with NSDate's -earlierDate: or -laterDate: methods.
Can any one tell that how to find the date for the 3rd day from the current date iphone/ipad.
Thanks in advance
You can use this:
NSDate *today = [[NSDate alloc] init];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
[offsetComponents setDay:3];
NSDate *threeDaysFromToday = [gregorian dateByAddingComponents:offsetComponents toDate:today options:0];
Slightly modified example from Apple's own documentation on NSDate. Check the link out for further info and more examples.
Here is Sample Code
NSDate * currentDate=[NSDate date];
NSTimeInterval interval=[currentDate timeIntervalSince1970];
NSTimeInterval intervalForThirdDate=interval+86400*3;
NSDate *nextDate=[[NSDate alloc]initWithTimeIntervalSince1970:intervalForThirdDate];
NSDate *today = [NSDate date];
NSTimeInterval threeDays = 86400*3;
NSDate *threeDaysFromToday = [NSDate dateWithTimeInterval:threeDays sinceDate:today];
choose one:
NSDate *futureDate;
NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
[components setDay:3];
futureDate = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:[NSDate date] options:0];
NSLog(#"%# - %#", [NSDate date], futureDate);
NSDate *futureDate = [[NSDate date] dateByAddingTimeInterval:3 * (24*60*60)];
[NSDate dateWithTimeIntervalSinceNow:86400*3]
But as someone mentioned above, DST might make this too inaccurate. Depends on how important that is.
Something like:
// get the gregorian calendar ready to go; use the getter for the current system
// calendar if you're happy to deal with other calendars too
NSCalendar *gregorianCalendar = [[NSCalendar alloc]
initWithCalendarIdentifier: NSGregorianCalendar];
// get an NSDate object that is three days in the future
NSDate *dateInFuture = [NSDate dateWithTimeIntervalSinceNow:3*24*60*60];
// grab the date components for the bits we want to print in this example
NSDateComponents *componentsOfDateInFuture =
[gregorianCalendar
components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
fromDate:dateInFuture];
// and print
NSLog(#"in three days it'll be %04d/%02d/%02d",
componentsOfDateInFuture.year,
componentsOfDateInFuture.month,
componentsOfDateInFuture.day);
// clean up
[gregorianCalendar release];
EDIT: Pablo Santa Cruz's answer is better for ensuring you're three days in the future, given daylight savings concerns. This is how you'd decompose an NSDate to day/month/year though, for the purposes of having the date rather than simply an NSDate.