How do I get the day of the week with Foundation?

问题

How do I get the day of the week as a string?

回答1:

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];  
[dateFormatter setDateFormat:@"EEEE"];
NSLog(@"%@", [dateFormatter stringFromDate:[NSDate date]]);

outputs current day of week as a string in locale dependent on current regional settings.

To get just a week day number you must use NSCalendar class:

NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDateComponents *comps = [gregorian components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
int weekday = [comps weekday];

回答2:

Just use these three lines:

CFAbsoluteTime at = CFAbsoluteTimeGetCurrent();
CFTimeZoneRef tz = CFTimeZoneCopySystem();
SInt32 WeekdayNumber = CFAbsoluteTimeGetDayOfWeek(at, tz);

回答3:

Many of the answers here are deprecated. This works as of iOS 8.4 and gives you the day of the week as a string and as a number.

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"EEEE"];
NSLog(@"The day of the week: %@", [dateFormatter stringFromDate:[NSDate date]]);

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *comps = [gregorian components:NSCalendarUnitWeekday fromDate:[NSDate date]];
int weekday = [comps weekday];
NSLog(@"The week day number: %d", weekday);

回答4:

Here's how you do it in Swift 3, and get a localised day name…

let dayNumber = Calendar.current.component(.weekday, from: Date()) // 1 - 7
let dayName = DateFormatter().weekdaySymbols[dayNumber - 1]

回答5:

-(void)getdate {
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyy-MM-dd"];
    NSDateFormatter *format = [[NSDateFormatter alloc] init];
    [format setDateFormat:@"MMM dd, yyyy HH:mm"];
    NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
    [timeFormat setDateFormat:@"HH:mm:ss"];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init] ;
    [dateFormatter setDateFormat:@"EEEE"];

    NSDate *now = [[NSDate alloc] init];
    NSString *dateString = [format stringFromDate:now];
    NSString *theDate = [dateFormat stringFromDate:now];
    NSString *theTime = [timeFormat stringFromDate:now];

    NSString *week = [dateFormatter stringFromDate:now];
    NSLog(@"\n"
          "theDate: |%@| \n"
          "theTime: |%@| \n"
          "Now: |%@| \n"
          "Week: |%@| \n"
         , theDate, theTime,dateString,week); 
}

回答6:

I needed a simple (Gregorian) day of the week index, where 0=Sunday and 6=Saturday to be used in pattern match algorithms. From there it is a simple matter of looking up the day name from an array using the index. Here is what I came up with that doesn't require date formatters, or NSCalendar or date component manipulation:

+(long)dayOfWeek:(NSDate *)anyDate {
    //calculate number of days since reference date jan 1, 01
    NSTimeInterval utcoffset = [[NSTimeZone localTimeZone] secondsFromGMT];
    NSTimeInterval interval = ([anyDate timeIntervalSinceReferenceDate]+utcoffset)/(60.0*60.0*24.0);
    //mod 7 the number of days to identify day index
    long dayix=((long)interval+8) % 7;
    return dayix;
}

回答7:

Here is the updated code for Swift 3

Code :

let calendar = Calendar(identifier: .gregorian)

let weekdayAsInteger = calendar.component(.weekday, from: Date())

To Print the name of the event as String:

 let dateFromat = DateFormatter()

datFormat.dateFormat = "EEEE"

let name = datFormat.string(from: Date())

回答8:

I think this topic is really useful, so I post some code Swift 2.1 compatible.

extension NSDate {

    static func getBeautyToday() -> String {
       let now = NSDate()
       let dateFormatter = NSDateFormatter()
       dateFormatter.dateFormat = "EEEE',' dd MMMM"
       return dateFormatter.stringFromDate(now)
    }

}

Anywhere you can call:

let today = NSDate.getBeautyToday()
print(today) ---> "Monday, 14 December"

Swift 3.0

As @delta2flat suggested, I update answer giving user the ability to specify custom format.

extension NSDate {

    static func getBeautyToday(format: String = "EEEE',' dd MMMM") -> String {
        let now = Date()
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = format
        return dateFormatter.string(from: now)
    }

}

回答9:

Vladimir's answer worked well for me, but I thought that I would post the Unicode link for the date format strings.

http://www.unicode.org/reports/tr35/tr35-25.html#Date_Format_Patterns

This link is for iOS 6. The other versions of iOS have different standards which can be found in the X-Code documentation.

回答10:

This way it works in Swift:

    let calendar = NSCalendar.currentCalendar()
    let weekday = calendar.component(.CalendarUnitWeekday, fromDate: NSDate())

Then assign the weekdays to the resulting numbers.

回答11:

I had quite strange issue with getting a day of week. Only setting firstWeekday wasn't enough. It was also necesarry to set the time zone. My working solution was:

 NSCalendar* cal = [NSCalendar currentCalendar];
 [cal setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
 [cal setFirstWeekday:1]; //Sunday
 NSDateComponents* comp = [cal components:( NSWeekOfMonthCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit | NSWeekCalendarUnit)  fromDate:date];
 return [comp weekday]  ;

回答12:

Swift 2: Get day of week in one line. (based on neoscribe answer)

let dayOfWeek  = Int((myDate.timeIntervalSinceReferenceDate / (60.0*60.0*24.0)) % 7)
let isMonday   = (dayOfWeek == 0)
let isSunday   = (dayOfWeek == 6)

回答13:

self.dateTimeFormatter = [[NSDateFormatter alloc] init];
self.dateTimeFormatter.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0]; // your timezone
self.dateTimeFormatter.locale = [NSLocale localeWithLocaleIdentifier:@"zh_CN"]; // your locale
self.dateTimeFormatter.dateFormat = @"ccc MM-dd mm:ss";

there are three symbols we can use to format day of week:

The following two documents may help you.

https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html

http://www.unicode.org/reports/tr35/tr35-31/tr35-dates.html#Date_Format_Patterns

Demo:

you can test your pattern on this website:

http://nsdateformatter.com/

来源：https://stackoverflow.com/questions/4269093/how-do-i-get-the-day-of-the-week-with-foundation

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