comment puis-je régler l'heure de NSDate existant?

Question

Comment régler le temps d'un NSDate existant?

C'est que j'ai une date (disons la date / heure), mais souhaitez ensuite mettre à un temps spécifique (par exemple 11:23) dire. Quelle est la meilleure façon de le faire dans l'objectif C?

Je regarde NSCalendar et voir des méthodes telles que dateByAddingComponents:toDate:options: et dateFromComponents:, mais ceux-ci ne semblent pas tout à fait frappé la marque pour ce que je dois ici. Par exemple:

1. dateFromComponents: - je dois travailler tous les composants pour que cela fonctionne, qui semble overkill
2. dateByAddingComponents:toDate:options: -. Je ne veux pas ajouter dans mon cas, mais plutôt « ensemble » le temps

Answer 1

NSDate *date = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier: NSGregorianCalendar];
NSDateComponents *components = [gregorian components: NSUIntegerMax fromDate: date];
[components setHour: 7];
[components setMinute: 59];
[components setSecond: 17];

NSDate *newDate = [gregorian dateFromComponents: components];

I use NSUIntegerMax instead of specific OR-combined bit masks because it's easier, but if you want to specify which data components to receive, be my guest.

Answer 2

iOS 7 Note: I'm putting this in a few of these questions because use of NSUIntegerMax no longer seems to work on iOS7, and using it caused me to chase my tail for about 3 hours. I just discovered that when I use NSUIntegerMax, NSDateComponentsignores set year. So for example this DOES NOT change the year:

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components:NSUIntegerMax fromDate:date];
[comps setYear:year];
return [gregorian dateFromComponents:comps];

Whereas this DOES:

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSUInteger timeComps = (NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit | NSTimeZoneCalendarUnit);
NSDateComponents *comps = [gregorian components:timeComps fromDate:date];
[comps setYear:year];
return [gregorian dateFromComponents:comps];

It may be an iOS7 bug or it may be that using NSUIntegerMax working was a fluke which no longer works. I will file a bug report and get a definitive answer.

Regardless, if you want to avoid unexpected consequences specify ALL the components else you might be chasing your tail!

Answer 3

Swift 2.0 version of how you'd set a given date to 8am

extension NSDate {

func setTo8AM() -> NSDate {
    let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
    let components = calendar.components(([.Day, .Month, .Year]), fromDate: self)
    components.hour = 8
    return calendar.dateFromComponents(components)!
}

}

Answer 4

Apply this to set the Time from an another date to an existing Date

NSDate *today = [NSDate date]; // from which i need only "Year" "Month" "Date"

NSCalendar *calendar = [NSCalendar currentCalendar]
NSDateComponents *dateComponents = [calendar components:( NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit ) fromDate:today];

NSDate *timeDate = datePicker.date; // from which i need only "Hours" "Minutes" and "Seconds"

NSDateComponents *timeComponents = [calendar components:( NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:timeDate];

            [dateComponents setHour:[timeComponents hour]];
            [dateComponents setMinute:[timeComponents minute]];
            [dateComponents setSecond:[timeComponents second]];

NSDate *newDate = [calendar dateFromComponents:dateComponents]; // New Date with My "Year" "Month" "Date" "Hours" "Minutes" and "Seconds" 

            NSLog(@"New Date: %@",newDate);

Answer 5

Here's a more generic Swift (v2.1.1) extension that builds on Andrew Schreiber's helpful answer.

extension NSDate {
    func dateWithTime(hour: Int, minute: Int, second: Int) -> NSDate? {
        let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
        let components = calendar.components(([.Day, .Month, .Year]), fromDate: self)
        components.hour = hour
        components.minute = minute
        components.second = second
        let newDate = calendar.dateFromComponents(components)
        return newDate
    }
}

Answer 6

A swift example. For my purposes, I wanted to get the date for around 12 noon tomorrow.

var tomorrow:NSDate = NSDate().dateByAddingTimeInterval(60*60*24); //60seconds*60minutes*12hours
var gregorian:NSCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!;
var unit : NSCalendarUnit = (NSCalendarUnit.YearCalendarUnit|NSCalendarUnit.MonthCalendarUnit|NSCalendarUnit.DayCalendarUnit|NSCalendarUnit.HourCalendarUnit|NSCalendarUnit.MinuteCalendarUnit);
var comps:NSDateComponents = gregorian.components(unit, fromDate: tomorrow);
comps.setValue(12, forComponent: NSCalendarUnit.HourCalendarUnit);
comps.setValue(0, forComponent: NSCalendarUnit.MinuteCalendarUnit);
var noon_tomorrow : NSDate = gregorian.dateFromComponents(comps)!;