NSDate使用大全

#define kDEFAULT_DATE_TIME_FORMAT (@"yyyy-MM-dd HH:mm:ss")

//获取当前日期，时间

+(NSDate *)getCurrentDate{

    NSDate *now = [NSDate date];

    return now;

}

//将日期转换为字符串（日期，时间）

+(NSString *)getDateStringFromDate:(NSDate *)date{

    NSInteger location = 0;

    NSString *timeStr = @"";

    NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];

    [formatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"] autorelease]];

    [formatter setDateFormat:@"HH:mm:a"];

    NSString *ampm = [[[formatter stringFromDate:date] componentsSeparatedByString:@":"] objectAtIndex:2];

    timeStr = [formatter stringFromDate:date];

    NSRange range = [timeStr rangeOfString:[NSString stringWithFormat:@":%@",ampm]];

    location = range.location;

    NSString *string = [timeStr substringToIndex:location];

    timeStr = [NSString stringWithFormat:@"%@ %@",ampm,string];

    

    

    NSString *dateStr = @"";

    NSDateFormatter *Dformatter = [[[NSDateFormatter alloc] init] autorelease];

    [Dformatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"] autorelease]];

    [Dformatter setDateFormat:@"yyyy-MM-dd"];    

    dateStr = [Dformatter stringFromDate:date];

//    NSLog(@"%@", [NSString stringWithFormat:@"%@  %@",dateStr,timeStr]);

    return [NSString stringWithFormat:@"%@  %@",dateStr,timeStr];

}

//计算两个日期之间的差距，过了多少天。。

+(NSInteger)getDateToDateDays:(NSDate *)date withSaveDate:(NSDate *)saveDate{

    NSCalendar* chineseClendar = [ [ NSCalendar alloc ] initWithCalendarIdentifier:NSGregorianCalendar ];  

    NSUInteger unitFlags =  NSHourCalendarUnit | NSMinuteCalendarUnit |  

    NSSecondCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit;  

    NSDateComponents *cps = [ chineseClendar components:unitFlags fromDate:date  toDate:saveDate  options:0];  

    NSInteger diffDay   = [ cps day ];  

    [chineseClendar release];

    return diffDay;

}

例：NSDate *lastDate = [self getSaveDate];//saveDate通过将NSDate转换为NSString来保存

    currentDate = [NSDate date];

    NSInteger day = [DateHelper getDateToDateDays:currentDate withSaveDate: lastDate];

//日期转字符串

+ (NSString * )NSDateToNSString: (NSDate * )date

{    

    NSDateFormatter * formatter = [[NSDateFormatter alloc] init];

    [formatter setDateFormat: kDEFAULT_DATE_TIME_FORMAT];

    NSString *dateString = [formatter stringFromDate:date];

    [formatter release];

    return dateString;

}

 

//字符串转日期

+ (NSDate * )NSStringToNSDate: (NSString * )string

{    

    NSDateFormatter * formatter = [[NSDateFormatter alloc] init];

    [formatter setDateFormat: kDEFAULT_DATE_TIME_FORMAT];

    NSDate *date = [formatter dateFromString :string];

    [formatter release];

    return date;

}

 

//1970年到现在的秒数转换成时间显示

- (NSString *)bySecondGetDate:(NSString *)second{

    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

    [formatter setDateFormat:@"yyyy年MM月dd日 HH:mm:ss"];

    NSString *dateLoca = [NSString stringWithFormat:@"%@",second];

    NSTimeInterval time=[dateLoca doubleValue];

    NSDate *detaildate=[NSDate dateWithTimeIntervalSince1970:time];

    NSString *timestr = [formatter stringFromDate:detaildate];

    return timestr;

}