In My application I have to complete a particular task in given time.So first i calculated the time complete the task in seconds and then add that time to the current that like this.
NSDate *mydate = [NSDate date];
NSTimeInterval TotalDuraionInSec = sec.cal_time * 60;
TaskCmpltTime = [mydate addTimeInterval:TotalDuraionInSec];
NSLog(#"task will be completed at%#",TaskCmpltTime);
now I compare time like this
if([CurrentTime isEqualToDate:AfterCmpltTime]){
NSLog (#"Time Finish");
}
but I want to know is Time is left or not.Is current time is less then or greater then current time how can i know this ?
timeIntervalSinceNow compares the NSDate with Now. if NSDate is after Now the return value is possitive, if the date is earlier than Now the result is negative.
double timeLeft = [TaskCompltTime timeIntervalSinceNow];
if( timeLeft > 0.0 )
// still time left
else
//time is up
I have an example where I get the time from a picker and check if its today or tomorrow. You should be able to just take the code and use it in your way...
int selectedHour = [customPickerView selectedRowInComponent:0];
int selectedMinute = [customPickerView selectedRowInComponent:1];
NSDate *today = [NSDate date];
NSDateFormatter *weekdayFormatter = [[[NSDateFormatter alloc] init]autorelease];
NSDateFormatter *hmformatter = [[[NSDateFormatter alloc] init]autorelease];
[hmformatter setDateFormat: #"hh mm"];
[weekdayFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
[weekdayFormatter setDateFormat: #"EE"];
// NSString *formattedDate = [formatter stringFromDate: today];
NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]autorelease];
NSDateComponents *dateComponentsToday = [gregorian components:(NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit) fromDate:today];
NSInteger currentHour = [dateComponentsToday hour];
NSInteger currentMinute = [dateComponentsToday minute];
NSString *weekday;
if ((selectedHour > currentHour) | ((selectedHour == currentHour) & (selectedMinute > currentMinute))) {
//so we are still in today
weekday = [weekdayFormatter stringFromDate: today];
weekday = NSLocalizedString(#"today", #"today");
} else {
//the timer should start tomorrow
NSTimeInterval secondsPerDay = 24 * 60 * 60;
NSDate *tomorrow = [today dateByAddingTimeInterval:secondsPerDay];
weekday = [weekdayFormatter stringFromDate: tomorrow];
weekday = NSLocalizedString(#"tomorrow", #"tomorrow");
}
Yeah, for your purposes it's probably best to work in time intervals. The NSTimeInterval in Objective-C is an alias for double, and it represents a time value in seconds (and, of course, fractions, down to at least millisecond resolution).
There are several methods on NSDate for this -- +timeIntervalSinceReferenceDate, which returns the number of seconds since Jan 1, 2001, -timeIntervalSinceReferenceDate, which returns the difference in time between the supplied NSDate object and Jan 1, 2001, -timeIntervalSinceDate:, which returns the difference in seconds between the two NSDate objects, and -timeIntervalSinceNow, which returns the difference between the current time and the NSDate object.
Lots of times it's most convenient to store an NSDate value as an NSTimeInterval instead (eg, timeIntervalSinceReferenceDate). This way it doesn't have to be retained and disposed, etc.
Related
I am trying to find how many milliseconds into the current day we are. I can't find a method to return the time in milliseconds ignoring date, so I figured I could calculate it off of the value returned by timeIntervalSince 1970 method.
I did this:
NSLog(#"%f", [[NSDate date] timeIntervalSince1970]);
2013-05-21 16:29:09.453 TestApp[13951:c07] 1369171749.453490
Now my assumption is that, since there are 86,400 seconds in a day I could divide this value by 86400 and get how many days have elapsed since 1970. Doing this gives me 15846.8952483 days. Now, if my assumption holds, I am 89.52483% through the current day. So multiple 24 hours by 86.52659% would give me a current time of the 21.4859592 hour or about 09:29 PM. As you can see from my NSLog this is about 5 hours from the real time, but I believe the interval returned is GMT so this would be 5 hours ahead of my time zone.
So I figured, well what the heck, I'll just roll with it and see what happens.
I cut off the decimal places by doing:
float timeSince1970 = [[NSDate date] timeIntervalSince1970]/86400.0;
timeSince1970 = timeSince1970 - (int)timeSince1970
Then calculate the milliseconds that have taken place thus far today:
int timeNow = timeSince1970 * 86400000;
NSLog(#"%i", timeNow);
2013-05-21 16:33:37.793 TestApp[14009:c07] 77625000
Then I convert the milliseconds (which still seem appropriate) to NSDate:
NSString *timeString = [NSString stringWithFormat:#"%d", timeNow];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:#"A"]
NSDate *dateNow = [dateFormatter dateFromString:timeString];
NSLog(#"%#", dateNow);
2013-05-21 16:29:09.455 TestApp[13951:c07] 2000-01-02 03:29:00 +0000
And there is my problem. Rather than returning a 2000-01-01 date with some hours and minutes attached, it is returning a 2000-01-02 date. Why!?
EDIT
I got it working by "removing" the extra 5 hours I noted in the above with:
int timeNow = (timeSince1970 * 86400000) - (5 * 60 * 60 * 1000);
I don't understand why this is necessary though. If someone can explain I'd greatly appreciate it.
EDIT 2
Perhaps I should be asking a more elementary question about how to accomplish the task I'm trying to accomplish. I care about times (for example, 4pm is important but I could care less about the date). I've been storing these in NSDates created by:
[dateFormatter setDateFormat:#"hh:mm a"];
[dateFormatter dateFromString#"04:00 PM"];
All this seems to be going fine. Now I want to compare current time to my saved time and find out if it is NSOrderedAscending or NSOrderedDescending and respond accordingly. Is there a better way to be accomplishing this?
You need to use NSCalendar to generate NSDateComponents based on right now, then set the starting hour, minute, and second all to 0. That will give you the beginning of today. Then you can use NSDate's -timeIntervalSinceNow method to get back the time elapsed between now and your start date.
NSCalendar *cal = [NSCalendar currentCalendar];
NSDate *now = [NSDate date];
// BUILD UP NSDate OBJECT FOR THE BEGINNING OF TODAY
NSDateComponents *comps = [cal components: (NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate: now];
comps.hour = 0;
comps.minute = 0;
comps.second = 0;
// USE CALENDAR TO GENERATE NEW DATE FROM COMPONENTS
NSDate *startOfToday = [cal dateFromComponents: comps];
// YOUR ELAPSED TIME
NSLog(#"%f", [startOfToday timeIntervalSinceNow]);
Edit 1
If you're just looking to compare some NSDateObjects you can see if the time interval between then and now is negative. If so, that date is in the past.
NSDate *saveDate = [modelObject lastSaveDate];
NSTimeInterval difference = [saveDate timeIntervalSinceNow];
BOOL firstDateIsInPast = difference < 0;
if (firstDateIsInPast) {
NSLog(#"Save date is in the past");
}
You could also use compare:.
NSDate* then = [NSDate distantPast];
NSDate* now = [NSDate date];
[then compare: now]; // NSOrderedAscending
The part of your question that says that you want to calculate "how many milliseconds into the current day we are" and then "4pm is important but I could care less about the date" makes it not answerable.
This is because "today" there could have been a time change, which changes the number of milliseconds since midnight (by adding or subtracting an hour, for instance, or a leap second at the end of a year, etc....) and if you don't have the date, you can't determine the number of milliseconds accurately.
Now, to address your edited question: If we assume today's date, then you need to use the time that you have stored and combine it with today's date to get a "specific point in time" which you can compare to the current date and time:
NSString *storedTime = #"04:00 PM";
// Use your current calendar
NSCalendar *cal = [NSCalendar currentCalendar];
// Create a date from the stored time
NSDateFormatter *dateFormatter = [NSDateFormatter new];
[dateFormatter setDateFormat:#"hh:mm a"];
NSDate *storedDate = [dateFormatter dateFromString:storedTime];
// Break it up into its components (ie hours and minutes)
NSDateComponents *storedDateComps = [cal components:NSHourCalendarUnit | NSMinuteCalendarUnit
fromDate:storedDate];
// Now we get the current date/time:
NSDate *currentDateAndTime = [NSDate date];
// Break it up into its components (the date portions)
NSDateComponents *todayComps = [cal components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
fromDate:currentDateAndTime];
// Combine with your stored time
todayComps.hour = storedDateComps.hour;
todayComps.minute = storedDateComps.minute;
// Create a date from the comps.
// This will give us today's date, with the time that was stored
NSDate *currentDateWithStoredTime = [cal dateFromComponents:todayComps];
// Now, we have the current date and the stored value as a date, so it is simply a matter of comparing them:
NSComparisonResult result = [currentDateAndTime compare:currentDateWithStoredTime];
it is returning a 2000-01-02 date. Why!?
Because your dateFormatter uses the current system locale's timezone.
If you insert ...
dateFormatter.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];
... your date formatter will interpret the string correctly. But why not creating the date directly:
NSDate *dateNow = [NSDate dateWithTimeIntervalSinceReferenceDate:timeNow];
I've tried all the time calculating examples I found on this site but somehow I'm getting 0 as value every time. I'm new to IOS and the NSDate is giving me a run for it's money :)
I want to record time A when I press button "startStop", and then record time B when I press it again. Pressing it a second time (deselecting) has to calculate the time elapsed between these 2 dates. So far I have this:
-(IBAction)buttonClick {
NSDate *startStopDate = [NSDate alloc];
NSDateFormatter *formatter= [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"hh:mm:ss"];
NSString *currentTime = [[NSString alloc] init];
NSString *currentTime2 = [[NSString alloc]init];
NSDate *start =[ [NSDate alloc]init];
NSDate *stop = [[NSDate alloc] init];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
if (startStop.selected==NO) {
NSLog(#"started");
[startStop setSelected:YES];
startStopDate = [NSDate date];
currentTime = [formatter stringFromDate:startStopDate];
NSLog(#"Current timestarted is %#",currentTime);
startTime.text = currentTime;
start = [formatter dateFromString:currentTime];
}
else {
NSLog(#"Selected");
[startStop setSelected:NO];
startStopDate = [NSDate date];
currentTime2 = [formatter stringFromDate:startStopDate];
NSLog(#"Current time is %#",currentTime2);
stopTime.text = currentTime2;
stop = [formatter dateFromString:currentTime2];
NSUInteger unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
NSDateComponents *components = [gregorianCalendar components:unitFlags
fromDate:start
toDate:stop
options:0];
NSInteger hours = [components hour];
NSInteger minutes = [components minute];
NSInteger seconds = [components second];
NSLog(#"hello %d, %d, %d", hours, minutes, seconds);
}
}
My labels give the correct hour:minute output when pressed, but I can't seem to get them to transfer to the date calculation.
I've been trying numerous variations with dateFromString and stringFromDate and multiple date/string objects as you can see, but so far I only get big negative numbers or just zero as result. Any help appreciated ;)
Greets, Nick
That's because start is a local variable. When the button is clicked the second time, your code will skip the if block and go straight to the else block, leaving the start variable allocated but not initialized to anything useful. You need to store this start value outside of a local context if you want to use it to calculate the difference between the start and stop times.
I live in the US eastern time zone (EST), and a couple weeks ago the daylight savings began. I was testing some of my earlier code, which was working(supposedly) fine and noticed that the day second calculations are running 1 hour earlier.
here's the code that I use for testing:
int gmtOffset = [[NSTimeZone localTimeZone] secondsFromGMT];
int daylightOffset = [[NSTimeZone localTimeZone] daylightSavingTimeOffset];
int daySeconds = ((int)([date timeIntervalSinceReferenceDate]+gmtOffset+daylightOffset))%(86400+1);
NSLog(#"Day seconds: %i", daySeconds);
The result is 3600 seconds less than the expected value. The daylightOffset is 0. How can I correctly get the daylight offset for the timezone that the user is in? the NSDateFormatter parses the date correctly, so it must know something that NSTimeZone is not telling me.
Thank you!
The [localTime secondsFromGMT] return the true GMT including the daylight saving time, you can get the offset itself by [localTime daylightSavingTimeOffset]
This seems to be a recurring problem for many (me included) and after having pulled my hair way too long I have finally solved the issue.
The assumptions this code relies on is that:
you are interested in dates, not in time
you want your date calculations to be oblivious to any Daylight Saving Time
you want an easy enough string representation of the date such that you can persist it.
In order to achive 1. I use unique NSCalendar instance that is initialized to Gregorian, GMT
This also serves 2.
For 3. the NSDateFormatter is initialized with both the unique calendar and its time zone.
Setting the timezone of the formatter to that of the calendar otherwise used for calculation was the key to all the issues I had!
This should always be true (assume the code below is part of a DateModel class):
NSDate * today = [DateModel normalize: [NSDate date]] ;
NSString*todayS= [DateModel dateToString: today] ;
BOOL alwaysTrue=[[DateModel normalize: [NSDate date]] isEqual: [DateModel stringToDate: todayS]] ;
Here's the code:
+ (NSDate *) normalize: (NSDate *) date {
NSDateComponents * comps = [[DateModel calendar] components:NSYearCalendarUnit
| NSMonthCalendarUnit
| NSDayCalendarUnit
| NSHourCalendarUnit
| NSMinuteCalendarUnit
| NSSecondCalendarUnit
fromDate:date] ;
[comps setHour:0] ;
[comps setMinute:0] ;
[comps setSecond:0] ;
NSDate * dateOnly = [[DateModel calendar] dateFromComponents:comps] ;
return dateOnly ;
}
+ (NSCalendar *) calendar {
static NSCalendar * calendar = nil ;
if (calendar == nil) {
calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] ;
calendar.timeZone = [NSTimeZone timeZoneWithAbbreviation: #"GMT"] ;
}
return calendar ;
}
+ (NSDateFormatter *) dateFormatter {
static NSDateFormatter * formatter = nil ;
if (formatter == nil) {
formatter = [[NSDateFormatter alloc] init] ;
[formatter setCalendar:[self calendar]] ; // <- This is
[formatter setTimeZone:[self calendar].timeZone] ; // <- critical
[formatter setDateFormat:#"yyyyMMdd"] ;
}
return formatter ;
}
+ (NSDate *) dateFromString: (NSString *) stringDate {
return [DateModel normalize: [[DateModel dateFormatter] dateFromString:stringDate]] ;
}
+ (NSString *) stringFromDate: (NSDate *) date {
return [[DateModel dateFormatter] stringFromDate:[DateModel normalize: date]] ;
}
Hope this helps someone!
If you want to determine the number of seconds since midnight, you can use date components. This code adjusts appropriately for daylight savings.
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setTimeZone:[NSTimeZone localTimeZone]];
NSDateComponents *comps = [calendar components:NSHourCalendarUnit|NSMinuteCalendarUnit| NSSecondCalendarUnit
fromDate:[NSDate date]];
NSInteger time = [comps hour] * 3600 + [comps minute] * 60 + [comps second];
NSLog(#"Day seconds: %i", time);
I've already tried with NSDate but with no luck.
I want the difference between for example 14:10 and 18:30.
Hours and minutes.
I Hope you can help me shouldn't be that complicated :)
There's no need to calculate this by hand, take a look at NSCalendar. If you want to get the hours and minutes between two dates, use something like this:
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSUInteger unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit;
NSDateComponents *components = [gregorianCalendar components:unitFlags
fromDate:firstDate
toDate:otherDate
options:0];
[gregorianCalendar release];
You now have the hours and minutes as NSDateComponents and can access them as NSIntegers like [components hour] and [components minute]. This will also work for hours between days, leap years and other fun stuff.
Here's my quick solution:
NSDateFormatter *df = [[[NSDateFormatter alloc] init] autorelease];
[df setDateFormat:#"HH:mm"];
NSDate *date1 = [df dateFromString:#"14:10"];
NSDate *date2 = [df dateFromString:#"18:09"];
NSTimeInterval interval = [date2 timeIntervalSinceDate:date1];
int hours = (int)interval / 3600; // integer division to get the hours part
int minutes = (interval - (hours*3600)) / 60; // interval minus hours part (in seconds) divided by 60 yields minutes
NSString *timeDiff = [NSString stringWithFormat:#"%d:%02d", hours, minutes];
The NSDate class has a method timeIntervalSinceDate that does the trick.
NSTimeInterval secondsBetween = [firstDate timeIntervalSinceDate:secondDate];
NSTimeInterval is a double that represents the seconds between the two times.
NSString *duration = [self calculateDuration:oldTime secondDate:currentTime];
- (NSString *)calculateDuration:(NSDate *)oldTime secondDate:(NSDate *)currentTime
{
NSDate *date1 = oldTime;
NSDate *date2 = currentTime;
NSTimeInterval secondsBetween = [date2 timeIntervalSinceDate:date1];
int hh = secondsBetween / (60*60);
double rem = fmod(secondsBetween, (60*60));
int mm = rem / 60;
rem = fmod(rem, 60);
int ss = rem;
NSString *str = [NSString stringWithFormat:#"%02d:%02d:%02d",hh,mm,ss];
return str;
}
I'm looking to get the current hour and minute on a user's iPhone for display in an app that doesn't show the status bar. Is there a simple way to do this?
// get current date/time
NSDate *today = [NSDate date];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
// display in 12HR/24HR (i.e. 11:25PM or 23:25) format according to User Settings
[dateFormatter setTimeStyle:NSDateFormatterShortStyle];
NSString *currentTime = [dateFormatter stringFromDate:today];
[dateFormatter release];
NSLog(#"User's current time in their preference format:%#",currentTime);
-(void)currentTime
{
//Get current time
NSDate* now = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *dateComponents = [gregorian components:(NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond) fromDate:now];
NSInteger hour = [dateComponents hour];
NSString *am_OR_pm=#"AM";
if (hour>12)
{
hour=hour%12;
am_OR_pm = #"PM";
}
NSInteger minute = [dateComponents minute];
NSInteger second = [dateComponents second];
[gregorian release];
NSLog(#"Current Time %#",[NSString stringWithFormat:#"%02ld:%02ld:%02ld %#", (long)hour, (long)minute, (long)second,am_OR_pm]);
}
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
[dateFormatter setTimeStyle:NSDateFormatterMediumStyle];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
NSString *currentTime = [dateFormatter stringFromDate:[NSDate date]]
[dateFormatter release]; dateFormatter = nil;
I think you should try this. The timeZone is important.
See this similar question for an answer. You will have to change it to your date format.
[[NSDate date] timeIntervalSince1970];
if you are looking to calculate time intervals, you are better off using CACurrentMediaTime
double currentTime = CACurrentMediaTime();
A shorter approach
NSDate * now = [NSDate date];
timeLabel.text = [NSDateFormatter localizedStringFromDate:now
dateStyle:NSDateFormatterNoStyle
timeStyle:NSDateFormatterShortStyle];
CFAbsoluteTimeGetCurrent()
Absolute time is measured in seconds relative to the absolute reference date of Jan 1 2001 00:00:00 GMT. A positive value represents a date after the reference date, a negative value represents a date before it. For example, the absolute time -32940326 is equivalent to December 16th, 1999 at 17:54:34. Repeated calls to this function do not guarantee monotonically increasing results. The system time may decrease due to synchronization with external time references or due to an explicit user change of the clock.