NSDateFormatterLongStyle string to NSDate - ios

Question

I have a UIDataPicker in my viewController with default location, when my user finishes selecting the date I run this code:
NSString *dateString = [NSDateFormatter localizedStringFromDate:[self.dataPicker date]
dateStyle:NSDateFormatterLongStyle
timeStyle:NSDateFormatterNoStyle];
With that code I can storage the date in the following format:
May 31, 2016
Later in my code I need to convert this string into a real date format, for this I use the code below:
-(NSDate*)convertStringToDate:(NSString*)date{
NSString *dateString = date;
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:#"en_US"];
[dateFormatter setDateFormat:#"MM/dd/yyyy"];
return [dateFormatter dateFromString:dateString];
}
But this code return a null value. As the datepicker is set by default, my system can receive any date format, but in the end I want it to be converted to the format en_us.
How I can solve this problem?

Answer 1

Don't store the date as a string; store it as an offset, in seconds, from some reference date.
i.e:
uint64_t offset = (uint64_t)[[self.dataPicker date] timeIntervalSinceReferenceDate];
// store this 64-bit unsigned integer.
This takes less space and is quicker to convert to/from an NSDate object.
You can leave the offset as an NSTimeInterval (64-bit floating point double) if you prefer, but as you aren't storing date & time, uint64_t should do...

Answer 2

Use this code,
-(NSDate*)convertStringToDate:(NSString*)date{
NSString *dateString = date;
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:#"en_US"];
[dateFormatter setDateFormat:#"MMM d, yyyy"];
return [dateFormatter dateFromString:dateString];
}
hope its helpful

Answer 3

The formatting string depends on the locale you are using. From the localizedStringFromDate documentation:
Returns string representation of a given date formatted for the
current locale using the specified date and time styles.
This method uses a date formatter configured with the current default
settings. The returned string is the same as if you configured and
used a date formatter as shown in the following example:
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.formatterBehavior = NSDateFormatterBehavior10_4;
formatter.dateStyle = dateStyle; formatter.timeStyle = timeStyle;
NSString *result = [formatter stringForObjectValue:date];
Means, you should do the next:
-(NSDate*)convertStringToDate:(NSString*)dateString {
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.formatterBehavior = NSDateFormatterBehavior10_4;
dateFormatter.dateStyle = NSDateFormatterLongStyle;
dateFormatter.timeStyle = NSDateFormatterNoStyle;
return [dateFormatter dateFromString:dateString];
}