Convert NSDate to NSString

问题:

How do I convert, NSDate to NSString so that only the year in @"yyyy" format is output to the string?

回答1:

How about...

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy"];

//Optionally for time zone conversions
[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"..."]];

NSString *stringFromDate = [formatter stringFromDate:myNSDateInstance];

//unless ARC is active
[formatter release];

Swift 4.2 :

func stringFromDate(_ date: Date) -> String {
    let formatter = DateFormatter()
    formatter.dateFormat = "dd MMM yyyy HH:mm" //yyyy
    return formatter.string(from: date)
}

回答2:

I don't know how we all missed this: localizedStringFromDate:dateStyle:timeStyle:

NSString *dateString = [NSDateFormatter localizedStringFromDate:[NSDate date] 
                                                      dateStyle:NSDateFormatterShortStyle 
                                                      timeStyle:NSDateFormatterFullStyle];
NSLog(@"%@",dateString);

outputs '13/06/12 00:22:39 GMT+03:00'

回答3:

Hope to add more value by providing the normal formatter including the year, month and day with the time. You can use this formatter for more than just a year

[dateFormat setDateFormat: @"yyyy-MM-dd HH:mm:ss zzz"]; 

回答4:

there are a number of NSDate helpers on the web, I tend to use:

https://github.com/billymeltdown/nsdate-helper/

Readme extract below:

  NSString *displayString = [NSDate stringForDisplayFromDate:date];

This produces the following kinds of output:

‘3:42 AM’ – if the date is after midnight today
‘Tuesday’ – if the date is within the last seven days
‘Mar 1’ – if the date is within the current calendar year
‘Mar 1, 2008’ – else ;-)

回答5:

In Swift:

var formatter = NSDateFormatter()
formatter.dateFormat = "yyyy"
var dateString = formatter.stringFromDate(YourNSDateInstanceHERE)

回答6:

  NSDateFormatter *dateformate=[[NSDateFormatter alloc]init];
  [dateformate setDateFormat:@"yyyy"]; // Date formater
  NSString *date = [dateformate stringFromDate:[NSDate date]]; // Convert date to string
  NSLog(@"date :%@",date);

回答7:

If you don't have NSDate -descriptionWithCalendarFormat:timeZone:locale: available (I don't believe iPhone/Cocoa Touch includes this) you may need to use strftime and monkey around with some C-style strings. You can get the UNIX timestamp from an NSDate using NSDate -timeIntervalSince1970.

回答8:

+(NSString*)date2str:(NSDate*)myNSDateInstance onlyDate:(BOOL)onlyDate{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    if (onlyDate) {
        [formatter setDateFormat:@"yyyy-MM-dd"];
    }else{
        [formatter setDateFormat: @"yyyy-MM-dd HH:mm:ss"];
    }

    //Optionally for time zone conversions
    //   [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"..."]];

    NSString *stringFromDate = [formatter stringFromDate:myNSDateInstance];
    return stringFromDate;
}

+(NSDate*)str2date:(NSString*)dateStr{
    if ([dateStr isKindOfClass:[NSDate class]]) {
        return (NSDate*)dateStr;
    }

    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyy-MM-dd"];
    NSDate *date = [dateFormat dateFromString:dateStr];
    return date;
}

回答9:

Just add this extension:

extension NSDate {
    var stringValue: String {
        let formatter = NSDateFormatter()
        formatter.dateFormat = "yourDateFormat"
        return formatter.stringFromDate(self)
    }
}

回答10:

If you are on Mac OS X you can write:

NSString* s = [[NSDate date] descriptionWithCalendarFormat:@"%Y_%m_%d_%H_%M_%S" timeZone:nil locale:nil];

However this is not available on iOS.

回答11:

swift 4 answer

static let dateformat: String = "yyyy-MM-dd'T'HH:mm:ss"
public static func stringTodate(strDate : String) -> Date
{

    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = dateformat
    let date = dateFormatter.date(from: strDate)
    return date!
}
public static func dateToString(inputdate : Date) -> String
{

    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = dateformat
    return formatter.string(from: inputdate)

}

回答12:

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:myNSDateInstance];
NSInteger year = [components year];
// NSInteger month = [components month];
NSString *yearStr = [NSString stringWithFormat:@"%ld", year];

回答13:

Define your own utility for format your date required date format for eg.

NSString * stringFromDate(NSDate *date)  
 {   NSDateFormatter *formatter
    [[NSDateFormatter alloc] init];  
    [formatter setDateFormat:@"MM ∕ dd ∕ yyyy, hh꞉mm a"];    
    return [formatter stringFromDate:date]; 
}

回答14:

It's swift format :

func dateFormatterWithCalendar(calndarIdentifier: Calendar.Identifier, dateFormat: String) -> DateFormatter {

    let formatter = DateFormatter()
    formatter.calendar = Calendar(identifier: calndarIdentifier)
    formatter.dateFormat = dateFormat

    return formatter
}


//Usage
let date = Date()
let fotmatter = dateFormatterWithCalendar(calndarIdentifier: .gregorian, dateFormat: "yyyy")
let dateString = fotmatter.string(from: date)
print(dateString) //2018