Maybe somebody can help explain why I am getting a null value when converting a string to a date. It all looks right but I'm obviously missing something here.
Some background:
This iPad app will be used in different countries and I will need to do a calculation on the date to see if 90 days have passed since a user last logged in.
I have a SQLite Database with a DateLastIn field set as TEXT
My Object has a DateLastIn property set as NSDate
When populating my record object I set up a NSDateFormatter as such..
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"]; // SQLite default date format
Then I read in the DateLastIn (Using FMDB wrapper for SQLite).
// test SQLite as String
NSString *testDate = [results stringForColumn:#"DateLastIn"];
NSLog(#"DateLastIn straight from DB (string) shows %#", testDate);
Result:
DateLastIn straight from DB (string) shows 2012-04-23 18:20:51
All is good so far. Next I test converting this to an NSDate object e.g
NSDate *aDate = [[NSDate alloc] init];
aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
Result:
Using formmater on string date results in: (null)
I have tried DATETIME in SQLite, I've tried using NSString in my object instead of NSDate and seem to be going around in circles.
Any help much appreciated.
NSDateFormatter uses the format patterns from the Unicode Technical Standard #35.
For the hour format, you need HH (Hour [0-23]) not hh (Hour [1-12]).
I changed your date format to HH not hh and it works. Here is my test code....
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"]; // SQLite default date format
// test SQLite as String
NSString *testDate = #"2012-04-23 18:20:51";
NSDate *aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
Related
Am Trying to convert NSString to NSDate and then store it on Core Data. I added the timezone to NSDateFormatter still it returns wrong output. And is stored in different format in Core Data.
NSString *dateString=#"2015-09-17 01:06:44";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
dateFormatter.locale = [NSLocale currentLocale];
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate *date_f = [dateFormatter dateFromString:dateString];
NSLog(#"date string %#",dateString);
NSLog(#"date %#",date_f);
NSManagedObject *events=[[NSManagedObject alloc] initWithEntity:entity insertIntoManagedObjectContext:app.context];
[events setValue:date_f forKey:#"start_date"];
Console Output was
date string 2015-09-17 01:06:44
date 2015-09-16 19:36:44 +0000
Data is stored in Core Data as below
start_date = "September 17, 2015";
Thanks.
This looks like a misunderstanding of time zone conversion. A thing that also gave me some headaches in the past :)
Here is what is done:
You have a date string
You tell that this date string is in local time zone
You convert the string to NSDate
NSDate is now an UTC date because there is no time zone information in a NSDate object
Now, about Core Data and NSManagedObject, you can check this answer. I don't know how your are currently getting this start_date value but first thing is to check you Core Data configuration.
Hope this helps.
Maybe somebody can help explain why I am getting a null value when converting a string to a date. It all looks right but I'm obviously missing something here.
Some background:
This iPad app will be used in different countries and I will need to do a calculation on the date to see if 90 days have passed since a user last logged in.
I have a SQLite Database with a DateLastIn field set as TEXT
My Object has a DateLastIn property set as NSDate
When populating my record object I set up a NSDateFormatter as such..
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"]; // SQLite default date format
Then I read in the DateLastIn (Using FMDB wrapper for SQLite).
// test SQLite as String
NSString *testDate = [results stringForColumn:#"DateLastIn"];
NSLog(#"DateLastIn straight from DB (string) shows %#", testDate);
Result:
DateLastIn straight from DB (string) shows 2012-04-23 18:20:51
All is good so far. Next I test converting this to an NSDate object e.g
NSDate *aDate = [[NSDate alloc] init];
aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
Result:
Using formmater on string date results in: (null)
I have tried DATETIME in SQLite, I've tried using NSString in my object instead of NSDate and seem to be going around in circles.
Any help much appreciated.
NSDateFormatter uses the format patterns from the Unicode Technical Standard #35.
For the hour format, you need HH (Hour [0-23]) not hh (Hour [1-12]).
I changed your date format to HH not hh and it works. Here is my test code....
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"]; // SQLite default date format
// test SQLite as String
NSString *testDate = #"2012-04-23 18:20:51";
NSDate *aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
I have a date picker in my app. The phone is set to Bangladesh local settings. When I select a date from datepicker is always returns the date in Bengali. It return a date in local format.
Like, it returns ০৬/১১/২০১৪
but I want it to be 06/11/2014.
I've tried converting it by date formatter. This is what I tried:
NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
[formatter setLocale:[NSLocale currentLocale]];
NSDate* date = [formatter dateFromString: self.birthDate.text];
NSDateFormatter *formater = [[NSDateFormatter alloc] init];
[formater setLocale:[NSLocale localeWithLocaleIdentifier:#"en_US"]];
[formater setDateFormat:#"dd/MM/yyyy"];
NSLog(#"%#",[formater stringFromDate:date]);
The output is null.
You are incorrect in your assumption when you say...
When I select a date from datepicker is always returns the date in Bengali. It return a date in local format.
UIDatePicker returns an NSDate object. NSDate has no formatting at all. It has no language, it is purely a point in time.
When you do this...
NSLog(#"%#", someDate);
The system will render that point in time into a string and then print it. It is the rendering into a string that contains the format.
I'm guessing what you are doing is this...
Get a date from a UIDatePicker.
Render that date into a UITextField in Bengali. (or label, or text view or something)
Trying to read the text and store it into a date.
Trying to then "convert" the date to an English string.
What you should be doing is just saving the date that comes from the date picker.
Put it into a property or something.
In your above code I think the bit that is failing is actually the first bit...
NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
[formatter setLocale:[NSLocale currentLocale]];
NSDate* date = [formatter dateFromString: self.birthDate.text];
Because you're not giving it a format it will fail. But this is the wrong way to go about it anyway.
You should have something like this...
- (void)datePickerChoseADate
{
self.date = self.datePicker.date;
}
I am new in iOS development. Actually I am trying to show some information which I get from a web service in a table view.
I have successfully retrieved the response as JSON in my code, but in my table view there is a label to show date.
But in my response the date is something like this
/Date(1391068800000)/
How can I convert this to show in my table view? I think this is Javascript date.
But I'm not sure how to convert it.
NSDate *date = [NSDate dateWithTimeIntervalSince1970:[your timestamp doublevalue]/1000];
divide value by 1000 cause of milliseconds (13 digit)
The date in your response is a timestamp. You can create a date object by:
NSDate *date = [NSDate dateWithTimeIntervalSince1970:1391068800000];
After that you can convert this date to a string in an appropriate format by using the NSDateFormatter class. For example:
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateStyle:NSDateFormatterMediumStyle];
NSString *dateString = [formatter stringFromDate:date];
For more information about formatting dates see: https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html
I am really stuck trying to compare dates in SQLite queries in Objective C. Here's what I'm doing:
Storing the date:
This document tells me to use the dateformat specified below, but it doesn't seem right. I tried using yyyy-MM-dd hh:mm:ss without success too though.
NSDate *today = [NSDate date];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"YYYY-MM-DD HH:MM:SS"];
NSString *dateString=[dateFormat stringFromDate:today];
NSString *query = [NSString stringWithFormat: #"INSERT INTO user (edited) VALUES (\"%#\")", dateString];
Comparing the date
I am using a timestamp for this, which I convert to a datetime string
long stamp = [sessie integerForKey:#"stamp"];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"YYYY-MM-DD HH:MM:SS"];
NSString *dateString = [formatter stringFromDate:[NSDate dateWithTimeIntervalSince1970:stamp]];
sqlite3_stmt *result = [db selectQuery:[NSString stringWithFormat:#"SELECT * FROM user WHERE edited > '%#'", dateString]];
The timestamp is simply generated using [[NSDate date] timeIntervalSince1970]. The problem is that the query won't give the correct results, and I don't even know if the date is stored correctly in the first place. Any help would be greatly appreciated!
A couple of observations:
For your date string, you do definitely do not want to use YYYY-MM-DD HH:MM:SS. That will not generate a valid date string. Using yyyy-MM-dd hh:mm:ss is much closer, but not quite right, either (since you'll use 12-hour hh). Use yyyy-MM-dd HH:mm:ss instead.
This date format, though, does not capture time zone, so, if you store date strings in your SQLite database, you should use UTC (GMT) as discussed in the SQLite Date And Time Functions documentation.
NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
formatter.timeZone = [NSTimeZone timeZoneWithName:#"UTC"];
formatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:#"en_US_POSIX"];
NSString *dateString = [formatter stringFromDate:today];
As shown above, you probably want to also specify the locale so that the format of the dates will not change depending upon the localization settings of the device.
Note that you might consider using timeIntervalSince1970 to store the date as a REAL value in your database (as opposed to a TEXT). This can be a little more efficient and automatically addresses the UTC issue.