使用扩展有清晰的代码

您可以编写一个扩展来将任何Date对象转换为任何所需的日历和格式

extension Date{
    func asString(format: String = "yy/MM/dd HH:mm",
                  for identifier: Calendar.Identifier = .persian) -> String {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: identifier)
        formatter.dateFormat = format
        
        return formatter.string(from: self)
    }
}

然后这样使用它:

let now = Date()

print(now.asString())  // prints -> 00/04/18 20:25
print(now.asString(format: "yyyy/MM/dd"))  // prints -> 1400/04/18
print(now.asString(format: "MM/dd", for: .gregorian))  //  prints -> 07/09  

要了解如何指定您想要的格式字符串，请查看此链接。 关于如何格式化日期的完整参考，请参阅Apple官方日期格式化指南。

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 ;-)

+(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;
}

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)

}

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

迅速:

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