NSDate and dateString in Objective-C - iphone

I want to save a date object to the backend of my App. This is the code:
NSDate *date = self.birthPickerView.date;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"YYYY-MM-dd HH:mm:ss"];
NSString *stringFromDate = [formatter stringFromDate:date];
NSLog(#"%#", stringFromDate);
NSDate *endDate = [formatter dateFromString:stringFromDate];
[formatter release];
NSLog(#"%#", endDate);
// Save to database
[user setObject:endDate forKey:#"birth"];
This is the print out result:
1985-03-05 00:00:00
1985-03-04 23:00:00 +0000
The end date is not right. I want to save 1985-03-05 in the database. Can you help me what is wrong?
Edit
[self.birthPickerView setTimeZone:[NSTimeZone localTimeZone]];
NSLog(#"%#", self.birthPickerView.date);
NSLog(#"%#", self.birthPickerView.timeZone);
[user setObject:self.birthPickerView.date forKey:self.navTitle];
This code save 1984-03-04 23:00:00 in database. what is wrong with it?

I don't see why would you need to convert your date into a string, and then back into the date again.
However, I'm pretty sure this happens because you didn't set the timezone on your NSDateFormatter. The default time zone is GMT which might cause the time offset you see there.

Related

Convert NSString to NSDate not correct

in my iPhone application I need to convert NSString to NSDate with formaT. Here is my code:
+(NSDate*)dateFromJsonString:(NSString*)string{
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"yyyy'-'MM'-'dd'T'HH':'mm':'ss'"];
NSLog(#"%#", [dateFormat dateFromString:string]);
return [dateFormat dateFromString:string];
}
If parameter "string" is 2013-05-30T15:53:02 after converting - [dateFormat dateFromString:string] it becomes 2013-05-30 12:53:02 +0000 , so there is a difference in 3 hours. How can I fix it?
You need to set the correct time zone. Here is a sample, correct it to the time zone of your server:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.timeZone = [NSTimeZone timeZoneWithAbbreviation:#"UTC"];
[dateFormatter setDateFormat:#"yyyy'-'MM'-'dd'T'HH':'mm':'ss'"];
return [dateFormatter dateFromString:dict[#"completed_at"]];
EDIT: You can check the available time zones with a class method on NSTimeZone:
+ (NSArray *)knownTimeZoneNames
Just output it to the console, and choose the time zone that corresponds to the server one.
EDIT 2: Probably this is more useful:
+ (NSDictionary *)abbreviationDictionary
Choose your time zone and than just change the #"UTC" in the code above with the desired abbreviation.
Try this dateFormat. Since timezone is not given in dateString, dateFormatter assumes it to be local timezone. If you know the timezone set it to formatter.
[dateFormat setDateFormat:#"yyyy-MM-dd'T'HH:mm:ss"];
Check this answer for more details.
This is TimeZone issue so use this code to fix this problem :
+(NSDate*)dateFromJsonString:(NSString*)string
{
NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:#"en-US"];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"yyyy'-'MM'-'dd'T'HH':'mm':'ss'"];
[dateFormat setLocale:locale];
[dateFormat setTimeZone:[NSTimeZone systemTimeZone]];
NSLog(#"%#", [dateFormat dateFromString:string]);
return [dateFormat dateFromString:string];
}
Hope it helps you.
You can use the following code to set timezone.
[dateFormatter setTimeZone:[NSTimeZone systemTimeZone]];
But before you try that, i should tell you that if you are logging the date, it will show it in UTC format and not in the timezone of your computer. So dont check your date by printing it. So try converting the date to string and printing it to check if the date is correct or not.
Try logging NSLog(#"%#",[dateFormatter stringFromDate:date]); first
You just need to set current time zone for date formatter. Because of it, you got some time difference. Use below code..
+(NSDate*)dateFromJsonString:(NSString*)string
{
NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
[inputFormatter setTimeZone:[NSTimeZone defaultTimeZone]];
[inputFormatter setDateFormat:#"YYYY-MM-dd'T'HH:mm:ss"];
NSDate *xExpDate = [inputFormatter dateFromString:string];
return xExpDate;
}

NSDate from NSString gives null result

I am using following code to generate NSDate -> NSString
+(NSString *)getCurrentTime
{
NSDate *now = [NSDate date];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"dd-MM-yyyy hh:MM:SS a"];
[dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSString* str =[dateFormatter stringFromDate:now];
[dateFormatter release];
NSLog(#"%#",str);
return str;
}
everything is fine in above code. I am using above code to store string in Database. Now while retrieving that string gives me NULL. Following is my code to retrieve date in specific format
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"hh:MM:SS a"];
[dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSDate *dt =[dateFormatter dateFromString:crdInfo.swipeTime];
NSLog(#"Date : %#",dt);
[dateFormatter release];
How should I retrieve or store with particular format?? My crdInfo.swipeTime is retrieving String propertly...
First off, why not just store the NSDate object or epoch timestamp? This will give you much more flexibility in the future.
Now to your problem, I suspect it is due to your configuration of the NSDateFormatter, you're saving it in one format and trying to convert it to a date using a different format. Make the formats the same and try again. If you want to display it differently than it is stored you're likely going to need to convert it to and NSDate using the stored format and then again use another date formatter to get it in the format you want it as a string.
As Narayana suggested you need to retrieve the date with same format as you have stored. Retrieve it as below : -
NSDateFormatter *reDateFormatter = [[NSDateFormatter alloc] init];
[reDateFormatter setDateFormat:#"dd-MM-yyyy hh:MM:SS a"];
[reDateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSDate *dt = [reDateFormatter dateFromString:str];
NSLog(#"The Date : %#",dt);
[reDateFormatter setDateFormat:#"hh:MM:SS a"];
NSString *currentTime = [reDateFormatter stringFromDate:dt];
NSLog(#"%#",currentTime);
Hope it helps you.
Try to format it to dd-MM-yyyy hh:mm:ss a.
You wrote dd-MM-yyyy hh:MM:SS a where MM in hh:MM:SS gives month which is unrecognized in this format and there is no point writing upercase SS for seconds
Hope you understand it.

Still having NSDateFormatter result issues even with NSTimezone properly set, why?

The result is still a day before, I'm just asking myself why, because the NSTimeZone is properly set and is the right one for my country (italy, rome)
here's my stub of code, any ideas?
NSString *dateString = #"03/07/2008";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setFormatterBehavior:[NSDateFormatter defaultFormatterBehavior]];
[formatter setDateFormat:#"dd/MM/yyyy"];
[formatter setLocale:[NSLocale currentLocale]];
[formatter setTimeZone:[NSTimeZone systemTimeZone]];
NSDate *dateFromString = [formatter dateFromString:dateString];
[formatter release];
the result in dateFromString is this 2008-07-02 22:00:00 +0000.
I've looked for other solutions but the common answer was to set the timezone correctly, in my case it is set properly but the problem still remains.
That is correct because by default the NSDate will return a UTC date in its description +0000. You are a couple of hours ahead of UTC so you get 22:00:00 for the day prior. I am -5 and my result UTC is 2008-07-03 04:00:00 +0000 (DST). The date is correct, it is just being displayed in UTC, if you are trying to display it correctly somewhere just use the date formatter to get a string again.
...
NSDate *dateFromString = [formatter dateFromString:dateString];
NSString *stringFromDate = [formatter stringFromDate:dateFromString];
[formatter release];
NSLog(#"%# : %#", dateFromString, stringFromDate);
2008-07-03 04:00:00 +0000 : 03/07/2008

Problem in setting nsdate value from a string

NSDate *My_StartDate,*My_EndDate ;
NSDateFormatter * df= [[NSDateFormatter alloc]init];
[df setDateFormat:#"dd/MM/yyyy hh:mm:ss"];
My_StartDate = [df dateFromString:#"01/05/2010 10:15:33"];
My_EndDate = [df dateFromString:#"01/05/2010 10:45:33"];
NSLog(#"%#",My_StartDate);
NSLog(#"%#",My_EndDate);
In the log i get something like this for the my_startdate as 2010-05-01 04:45:33 +0000 and end date as 2010-05-01 05:15:33 +0000 instead i should have got value as for start date as 2010-05-01 10:15:33 +0000 and end date as 2010-05-01 10:45:33 +0000
Try with below function:
-(NSString *)getDateStringFromDate :(NSDate *)dateValue{
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"yyyy-MM-dd"];
NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setTimeStyle:NSDateFormatterShortStyle];
[timeFormat setDateFormat:#"HH:mm:ss"];
//[timeFormat setDateFormat:#"HH:mm"];
//[timeFormat setDateFormat:#"HH:mm a"];
////
NSString *theDate = [dateFormat stringFromDate:dateValue];
NSString *theTime = [timeFormat stringFromDate:dateValue];
NSLog(#"\n"
"theDate: |%#| \n"
"theTime: |%#| \n"
, theDate, theTime);
return theDate;
}
Change Format of data as per your need.
Let me know in case of any difficulty.
Cheers.
This shows date which follow American standard time string but by this reason you don't get any problem in making your logic.Also
[df setDateFormat:#"dd/MM/yyyy hh:mm:ss"];
this format using 12 hour format (means 2:03 pm and 2:03 am) and date object never use am and pm for showing date object value but when you convert it correctly then it gives you right date and time.
If you feel you get any problem then use different locale for that.
It is displaying asper the GMT+4.30 time.It displays like that only.When you are converting that date to string using the DateFormatter it gives the same date(Whichever you want like start date as 01/05/2010 10:15:33 and end date as 01/05/2010 10:45:33).
NSDateFormatter * dateformatter= [[NSDateFormatter alloc]init];
[dateformatter setDateFormat:#"dd/MM/yyyy hh:mm:ss"];
NSString *dat = [dateformatter stringfromDate:My_StartDate];
then you will get the output as 01/05/2010 10:15:33
You might want to set the time zone of the date formatter to GMT here. Do it using
[df setTimeZone:[NSTimeZone timeZoneWithName:#"GMT"]];
before you do dateFromString: calls. This will give you what you want.
Just need to update here in your code:
I might be like that your time would be in 24 hours format, so at that time you need to use this ....other than that you need to set the timezone.
Follow this link for All zone : http://unicode.org/reports/tr35/tr35-6.html#Date%5FFormat%5FPatterns
[df setDateFormat:#"dd/MM/yyyy hh:mm:ss"];
to
[df setDateFormat:#"dd/MM/yyyy HH:mm:ss"];
You are Done ;)

is there any easy way to get Date?

I'm new to iPhone development. I want to set default date to NSDate Object as string. I don't see any easy way or method...
I think there might be a method in NSCalender? If there's such a method, please tell me.
Thanks in advance.
I'm not totally clear on what you are asking, but to create an instance of an NSDate object with the current date, one calls:
NSDate * myDate = [NSDate date];
If you are saying that you have a c-string or NSString that needs to be parsed to initialize an NSDate object, that's another question.
I have some code posted here:
How get a datetime column in SQLite with Objective C
that shows how to create NSDates from NSStrings using NSDateFormatter.
If you want to create an NSDate from a string, you need to use an NSDateFormatter to do it. It's important to note that the formatter will use the current locale's time zone when constructing the date, unless you put a time-zone in as part of the format. For more information about constructing time zones, see NSTimeZone.
For example, to create a date using the ubiquitous format '2011-01-16 00:00' in UTC, you would do:
NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm"];
// Only certain abbreviations are okay, like UTC. See docs for more info
[formatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"UTC"]];
NSDate* midnight_26_jan_2011_utc = [formatter dateFromString:#"2011-01-26 00:00"];
// this will display in your system locale
// (for me, it shows 2011-01-25 19:00 +0500 because I'm America/New_York time)
NSLog(#"date: %#", midnight_26_jan_2011_utc);
[formatter release];
Edit: Added time to format string.
You will need to look at the NSDate and NSDateFormatter classes. Here's a simple example of how to use them:
NSString* defaultDateString = [NSString stringWithFormat:#"2011-01-22 15:30:00"];
NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate* defaultDate = [dateFormatter dateFromString:defaultDateString];
[dateFormatter release];
and if you wanted to get the string from a date you can just use:
NSString* defaultDateString = [dateFormatter stringFromDate:defaultDate];
NSDateFormatter *DateFormatter=[[NSDateFormatter alloc] init];
[DateFormatter setTimeZone:[NSTimeZone defaultTimeZone]];
[DateFormatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"]; //here,you can set the date format as you need
NSDate *now = [[[NSDate alloc] init]autorelease];
NSString *theDate = [DateFormatter stringFromDate:now];
Now, you can use the string the date. :)
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc]init]autorelease];
[dateFormatter setDateFormat:#"yyyy-mm-dd"];
NSDate *yourDate = [dateFormatter dateFromString:#"2011-01-26"];