迅速回答

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)

}

如何……

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)
}

网络上有很多NSDate的助手，我倾向于使用:

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

自述摘录如下:

  NSString *displayString = [NSDate stringForDisplayFromDate:date];

这将产生以下类型的输出:

‘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 ;-)

objective - c:

NSDate *date = [NSDate dateWithTimeIntervalSinceNow:0];
NSDateFormatter *formatter = [NSDateFormatter new];
formatter.dateFormat = @"yyyy";
NSString *dateString = [formatter stringFromDate:date];

迅速:

let now = Date()
let formatter = DateFormatter()
formatter.dateFormat = "yyyy"
let dateString = formatter.string(from: now) 

这是nsdateformatter的一个好网站。您可以在不同的本地使用不同的DateFormatter预览日期字符串。

迅速:

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

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