Time from a TextView into NSDate - objective-c

Question

I'm building an iPhone app to take times: a car has to get at a given time at a point, so if the car is sooner or later, gets points.
I need to obtain the most precise timing as I can, so I want to use milliseconds, but as far results are disappointing.
The time is typed on a TextField, let's say 12:17:22 and the code is the following:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
[dateFormatter setDateFormat:#"HH:mm:ss"];
timeLegStart = [NSDate new];
timeLegStart = [dateFormatter dateFromString:setStartTime.text];
NSLog(#"timeLegStart = %#",timeLegStart);
The output is 1970-01-01 11:17:22 +0000, and I'd like it to be 12:17:22:000

Answer 1

Set your NSDateFormatter's properties like this (replacing with your time zone info):
NSDateFormatter * dateFormatter = [[NSDateFormatter alloc] init];
NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:#"pt_BR"];
[dateFormatter setTimeZone:[NSTimeZone timeZoneWithName:#"America/Sao_Paulo"]];
[dateFormatter setDateFormat:#"HH':'mm':'ss' 'z"];
[dateFormatter setLocale:locale];

Answer 2

The problem here is that NSDate comprises of date and time and they are not separately available. When you are giving the input date with time specs only it load the calendar start date values with the time you provided and creates a date. Hence here comes the date as output.
Actually there is no problem to work with that.
You can use the same formatter to get the time retrieved back:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
[dateFormatter setDateFormat:#"HH:mm:ss"];
NSDate* timeLegStart = [NSDate new];
timeLegStart = [dateFormatter dateFromString:#"12:12:12"];
NSLog(#"timeLegStart = %#",[dateFormatter stringFromDate:timeLegStart]);
It will give you:
timeLegStart = 12:12:12
EDIT : when logging NSDate it will be in GMT format only.Since you set the timezone to local there date will be always displayed like what you got.
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
[dateFormatter setDateFormat:#"HH:mm:ss"];
NSDate* timeLegStart = [NSDate new];
timeLegStart = [dateFormatter dateFromString:#"12:12:12"];
NSLog(#"timeLegStart = %#",timeLegStart);
Will give you:
2000-01-01 12:12:12 +0000

Answer 3

Well, I've sorted it out this way:
- (void)fijaTiempoInicio
{
//getting current day
NSDateComponents *dateComponents = [[NSCalendar currentCalendar] components:~ NSTimeZoneCalendarUnit fromDate:[NSDate date]];
[dateComponents setTimeZone:[NSTimeZone timeZoneWithName:#"Europe/Spain"]];
NSDate *currentDate = [[NSCalendar currentCalendar] dateFromComponents:dateComponents];
//extracting year, month and day from current date
NSDateFormatter *df = [[NSDateFormatter alloc]init];
[df setDateFormat:#"dd"];
NSString *currentDayString = [NSString stringWithFormat:#"%#",[df stringFromDate:currentDate]];
[df setDateFormat:#"MM"];
NSString *currentMonthString = [NSString stringWithFormat:#"%#",[df stringFromDate:currentDate]];
[df setDateFormat:#"yyyy"];
NSString *currentYearString = [NSString stringWithFormat:#"%#", [df stringFromDate:currentDate]];
NSDateFormatter *ft = [[NSDateFormatter alloc]init];
[ft setTimeZone:[NSTimeZone localTimeZone]];
[ft setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSString *tempDate = [NSString stringWithFormat:#"%#-%#-%# %#",currentYearString,currentMonthString,currentDayString,txtTiempoInicioTramo.text];
NSLog(#"tempDate= %#",tempDate);
startTime = [ft dateFromString:tempDate];
NSLog(#"startTime= %#",startTime);
Then, anothe method calculate the difference between two NSDates, which is a figure in milliseconds -a float
- (IBAction)btnCapturarTiempo:(id)sender
{
NSDateFormatter *formatCarTime = [[NSDateFormatter alloc]init];
[formatCarTime setDateFormat:#"HH:mm:ss"];
[formatCarTime setTimeZone:[NSTimeZone timeZoneWithName:#"Europe/Madrid"]];
carTime = [NSDate date];
difference = [carTime timeIntervalSinceDate:startTime];
labelTiempoCoche.text = [NSString stringWithFormat:#"%f",difference];