I am using following code in Xcode:
(void)updateLabel
{
NSDate* now = [NSDate date];
int hour = 23 - [[now dateWithCalendarFormat:nil timeZone:nil] hourOfDay];
int min = 59 - [[now dateWithCalendarFormat:nil timeZone:nil] minuteOfHour];
int sec = 59 - [[now dateWithCalendarFormat:nil timeZone:nil] secondOfMinute];
countdownLabel.text = [NSString stringWithFormat:#"%02d:%02d:%02d", hour, min,sec];
}
And am getting the following error. How can I fix this?
error: invalid operands to binary - (have 'int' and 'id')
You must be using this way :-
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dateComponents = [gregorian components:(NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate:[NSDate date]];
NSInteger hour = [dateComponents hour];
NSInteger minute = [dateComponents minute];
NSInteger second = [dateComponents second];
[gregorian release];
Hope it helps you
Use this way
NSDate* now = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dateComponents = [gregorian components:(NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate:now];
long hour =23-[dateComponents hour];
long min =59-[dateComponents minute];
long sec =59-[dateComponents second];
NSString *str = [NSString stringWithFormat:#"%02ld:%02ld:%02ld", hour, min,sec];
NSLog(#"--> %#",str);
Trying to combine these two dates with NSDateComponents
"2012-09-03 00:00:00 +0000" &
"1970-01-01 08:00:00 +0000"
With the following code I get --> 2012-09-02 11:00:00 +0000
unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
NSDateComponents *comps = [[NSCalendar currentCalendar] components:unitFlags fromDate:session.date];
NSDate *day3 = [[NSCalendar currentCalendar] dateFromComponents:comps];
unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
comps = [[NSCalendar currentCalendar] components:unitFlags fromDate:session.start];
comps.timeZone = [NSTimeZone timeZoneWithName:#"UTC"];
day3 = [[NSCalendar currentCalendar] dateByAddingComponents:comps toDate:day3 options:0];
Found the solution.
Here is the answer:
unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
cal.timeZone = [NSTimeZone timeZoneWithName:#"UTC"]; <--this is key
NSDateComponents *comps = [cal components:unitFlags fromDate:session.date];
comps.hour = 0;
comps.minute = 0;
NSDate *day3 = [cal dateFromComponents:comps];
unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
NSDateComponents *hourComps = [cal components:unitFlags fromDate:session.start];
day3 = [cal dateByAddingComponents:hourComps toDate:day3 options:0];
The result given the dates above should be 2012-09-02 08:00:00 +0000
What is the most efficient way to obtain an NSDate object that represents midnight of the current day?
New API in iOS 8
iOS 8 includes a new method on NSCalendar called startOfDayForDate, which is really easy to use:
let startOfToday = NSCalendar.currentCalendar().startOfDayForDate(NSDate())
Apple's description:
This API returns the first moment date of a given date.
Pass in [NSDate date], for example, if you want the start of "today".
If there were two midnights, it returns the first. If there was none, it returns the first moment that did exist.
Update, regarding time zones:
Since startOfDayForDate is a method on NSCalendar, it uses the NSCalendar's time zone. So if I wanted to see what time it was in New York, when today began in Los Angeles, I could do this:
let losAngelesCalendar = NSCalendar.currentCalendar().copy() as! NSCalendar
losAngelesCalendar.timeZone = NSTimeZone(name: "America/Los_Angeles")!
let dateTodayBeganInLosAngeles = losAngelesCalendar.startOfDayForDate(NSDate())
dateTodayBeganInLosAngeles.timeIntervalSince1970
let dateFormatter = NSDateFormatter()
dateFormatter.dateStyle = .MediumStyle
dateFormatter.timeStyle = .ShortStyle
dateFormatter.timeZone = NSTimeZone(name: "America/New_York")!
let timeInNewYorkWhenTodayBeganInLosAngeles = dateFormatter.stringFromDate(dateTodayBeganInLosAngeles)
print(timeInNewYorkWhenTodayBeganInLosAngeles) // prints "Jul 29, 2015, 3:00 AM"
Try this:
NSDate *const date = NSDate.date;
NSCalendar *const calendar = NSCalendar.currentCalendar;
NSCalendarUnit const preservedComponents = (NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay);
NSDateComponents *const components = [calendar components:preservedComponents fromDate:date];
NSDate *const normalizedDate = [calendar dateFromComponents:components];
NSCalendar *cal = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
[cal setTimeZone:[NSTimeZone systemTimeZone]];
NSDateComponents * comp = [cal components:( NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit) fromDate:[NSDate date]];
[comp setMinute:0];
[comp setHour:0];
[comp setSecond:0];
NSDate *startOfToday = [cal dateFromComponents:comp];
If you mean midnight as 23:59 then set component's hour as 23 and minutes as 59.
Swift:
let cal = NSCalendar.currentCalendar()
//tip:NSCalendarUnit can be omitted, but with the presence of it, you can take advantage of Xcode's auto-completion
var comps = cal.components(NSCalendarUnit.YearCalendarUnit | .MonthCalendarUnit | .DayCalendarUnit | .HourCalendarUnit | .MinuteCalendarUnit | .SecondCalendarUnit, fromDate: NSDate())
comps.hour = 0
comps.minute = 0
comps.second = 0
let midnightOfToday = cal.dateFromComponents(comps)!
Swift 2.2:
let cal = NSCalendar.currentCalendar()
let comps = cal.components([.Year, .Month, .Day, .Hour, .Minute, .Second], fromDate: NSDate())
comps.hour = 0
comps.minute = 0
comps.second = 0
let midnightOfToday = cal.dateFromComponents(comps)!
Objective-C:
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *comps = [cal components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute) fromDate:[NSDate date]];
[comps setHour:0];
[comps setMinute:0];
[comps setSecond:0];
NSDate *midnightOfToday = [cal dateFromComponents:comps];
You could use the following method to get the midnight value for an NSDate.
- (NSDate *)dateAtBeginningOfDayForDate:(NSDate *)inputDate
{
// Use the user's current calendar and time zone
NSCalendar *calendar = [NSCalendar currentCalendar];
NSTimeZone *timeZone = [NSTimeZone systemTimeZone];
[calendar setTimeZone:timeZone];
// Selectively convert the date components (year, month, day) of the input date
NSDateComponents *dateComps = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:inputDate];
// Set the time components manually
[dateComps setHour:0];
[dateComps setMinute:0];
[dateComps setSecond:0];
// Convert back
NSDate *beginningOfDay = [calendar dateFromComponents:dateComps];
return beginningOfDay;
}
Thkis is taken from here website.
From iOS8, you can use startDayForDate.
So, in order to get the start of today (Objective -C):
NSDate * midnight;
midnight = [[NSCalendar currentCalendar] startOfDayForDate: [NSDate date]];
try this:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *now = [NSDate date];
NSDateComponents *components = [gregorian components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:now];
NSDateFormatter* df = [[NSDateFormatter alloc]init];
[df setDateFormat:#"MM/dd/yyyy HH:mm:ss.SSS"];
NSLog(#"%#",[df stringFromDate:[gregorian dateFromComponents:components]]);
NSDate *now = [NSDate date];
NSDate *beginningOfToday = nil;
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&beginningOfToday interval:NULL forDate:now];
You could use NSCalendar's dateBySettingHour:minute:second:ofDate:options:
So it would be as easy as doing:
NSCalendar *calendar = [NSCalendar currentCalendar];
calendar.timeZone = [NSTimeZone timeZoneWithName:#"UTC"];
NSDate *midnight = [calendar dateBySettingHour:0 minute:0 second:0 ofDate:[NSDate date] options:0];
let calendar = NSCalendar.currentCalendar()
let unitFlags: NSCalendarUnit = [.Year, .Month, .Day, .Minute, .Second]
let components = calendar.components(unitFlags , fromDate: NSDate())
components.hour = 0
components.minute = 0
components.second = 0
//Gives Midnight time of today
let midnightOfToday = calendar.dateFromComponents(components)!
How can I create an NSDate with today's date and an hour, minutes, and seconds of 5, 0, and 0 respectively? I.e. the date will be 07/02/2010 05:00:00
//Gives us the current date
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorian components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:[NSDate date]];
[components setHour:5];
NSDate * date = [gregorian dateFromComponents:components];
[gregorian release];
Something along those lines should do the trick.
I'm trying to figure out what day (i.e. Monday, Friday...) of any given date (i.e. Jun 27th, 2009)
Thank you.
I've been doing:
NSDateFormatter* theDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[theDateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
[theDateFormatter setDateFormat:#"EEEE"];
NSString *weekDay = [theDateFormatter stringFromDate:[NSDate date]];
This has the added bonus of letting you choose how you'd like the weekday to be returned (by changing the date format string in the setDateFormat: call
Lots more information at:
http://developer.apple.com/documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html#//apple_ref/doc/uid/TP40002369
You may have a look to the NSDate and NSCalendar classes.
For example, here and here
They provide the following code:
NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents =
[gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:today];
NSInteger day = [weekdayComponents day];
NSInteger weekday = [weekdayComponents weekday];
Use NSCalendar and NSDateComponents. As shown in the NSDateComponents documentation:
NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [gregorian dateFromComponents:comps];
NSDateComponents *weekdayComponents = [gregorian components:NSWeekdayCalendarUnit fromDate:date];
int weekday = [weekdayComponents weekday];
Here's what I wound up with, which works exactly as intended. It takes a date, alters the date to be the first of the month, and gets the day of that date:
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:date];
NSDateComponents *monthDateComponents = [[NSCalendar currentCalendar] components: NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear |
NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond fromDate: date];
// build date as start of month
monthDateComponents.year = components.year;
monthDateComponents.month = components.month;
monthDateComponents.day = 1;
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
// [gregorian setFirstWeekday:1];
NSDate *builtDate =[gregorian dateFromComponents: monthDateComponents];
// NSDateComponents *weekdayComponents =[gregorian components: NSCalendarUnitWeekday fromDate: builtDate];
NSDateFormatter *df = [NSDateFormatter new];
[df setDateFormat:#"E"];
NSString *firstDay = [df stringFromDate:builtDate];
if([firstDay isEqual:#"Sun"]) // do for the other 6 days as appropriate
return 7;