将NSDate转换为NSString

问题描述 投票：250回答：14

如何将NSDate转换为NSString，以便仅将@“ yyyy”]]格式的年份输出到字符串？

如何将NSDate转换为NSString，以便仅将@“ yyyy”格式的年份输出到字符串？] >> [[

怎么样...

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) } 
我不知道我们怎么都错过了这个：
localizedStringFromDate:dateStyle:timeStyle:
NSString *dateString = [NSDateFormatter localizedStringFromDate:[NSDate date] 
                                                      dateStyle:NSDateFormatterShortStyle 
                                                      timeStyle:NSDateFormatterFullStyle];
NSLog(@"%@",dateString);

输出'13 / 06/12 00:22:39 GMT + 03：00'
 
希望通过提供包括时间，年份，月份和日期在内的常规格式器来增加更多的价值。您可以使用此格式程序超过一年的时间
[dateFormat setDateFormat: @"yyyy-MM-dd HH:mm:ss zzz"]; 

 
网络上有很多NSDate助手，我倾向于使用：
https://github.com/billymeltdown/nsdate-helper/
下面的自述文件摘录：
  NSString *displayString = [NSDate stringForDisplayFromDate:date];

这将产生以下几种输出：
‘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 ;-)

 
在Swift中：
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);

 
[如果您没有NSDate -descriptionWithCalendarFormat:timeZone:locale:（我不认为iPhone / Cocoa Touch包含此功能），则可能需要使用strftime和Monkey来配合一些C风格的字符串。您可以使用NSDate从NSDate -timeIntervalSince1970获取UNIX时间戳。
 
+(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;
}

 
只需添加此扩展名：
extension NSDate {
    var stringValue: String {
        let formatter = NSDateFormatter()
        formatter.dateFormat = "yourDateFormat"
        return formatter.stringFromDate(self)
    }
}

 
如果您使用的是Mac OS X，则可以编写：
NSString* s = [[NSDate date] descriptionWithCalendarFormat:@"%Y_%m_%d_%H_%M_%S" timeZone:nil locale:nil];

但是此功能在iOS上不可用。
 
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];

 
定义您自己的实用程序以格式化您的日期和所需的日期格式例如。
NSString * stringFromDate(NSDate *date)  
 {   NSDateFormatter *formatter
    [[NSDateFormatter alloc] init];  
    [formatter setDateFormat:@"MM ∕ dd ∕ yyyy, hh꞉mm a"];    
    return [formatter stringFromDate:date]; 
}

 
快速格式：
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

 
swift 4的答案
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)

}
objective-c swift nsstring nsdate
14个回答
463
投票
怎么样...
2
投票
如果您使用的是Mac OS X，则可以编写：

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

0
投票
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];
0
投票
定义您自己的实用程序以格式化您的日期和所需的日期格式例如。

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

0
投票
快速格式：

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

0
投票
swift 4的答案

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) }

282
投票
我不知道我们怎么都错过了这个：

localizedStringFromDate:dateStyle:timeStyle:

86
投票
希望通过提供包括时间，年份，月份和日期在内的常规格式器来增加更多的价值。您可以使用此格式程序超过一年的时间

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

24
投票
网络上有很多NSDate助手，我倾向于使用：

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

13
投票
在Swift中：

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

8
投票
NSDateFormatter *dateformate=[[NSDateFormatter alloc]init]; [dateformate setDateFormat:@"yyyy"]; // Date formater NSString *date = [dateformate stringFromDate:[NSDate date]]; // Convert date to string NSLog(@"date :%@",date);
4
投票
[如果您没有NSDate -descriptionWithCalendarFormat:timeZone:locale:（我不认为iPhone / Cocoa Touch包含此功能），则可能需要使用strftime和Monkey来配合一些C风格的字符串。您可以使用NSDate从NSDate -timeIntervalSince1970获取UNIX时间戳。
4
投票
+(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; }
3
投票
只需添加此扩展名：

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

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