NSDate+Helper.m

//
//  NSDate+Helper.m
//  JZB
//
//  Created by Jin Jin on 11-4-15.
//  Copyright 2011年 __MyCompanyName__. All rights reserved.
//

#import "NSDate+Helper.h"


@implementation NSDate (NSDate_Helper)

/*
 
 * This guy can be a little unreliable and produce unexpected results,
 
 * you’re better off using daysAgoAgainstMidnight
 
 */

//获取年月日如:19871127.

- (NSString *)getFormatYearMonthDay

{
    
    NSString *string = [NSString stringWithFormat:@"%d%02d%02d",[self getYear],[self getMonth],[self getDay]];
    
    return string;
    
}

//返回当前月一共有几周(可能为4,5,6)

- (int )getWeekNumOfMonth

{
    return [[self endOfMonth] getWeekOfYear] - [[self beginningOfMonth] getWeekOfYear] + 1;
    
}

//该日期是该年的第几周

- (int )getWeekOfYear

{
    
    int i;
    
    int year = [self getYear];
    
    NSDate *date = [self endOfWeek];
    
    for (i = 1;[[date dateAfterDay:-7 * i] getYear] == year;i++)
        
    {
        
    }
    
    return i;
    
}

//返回day天后的日期(若day为负数,则为|day|天前的日期)

- (NSDate *)dateAfterDay:(int)day

{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    // Get the weekday component of the current date
    
    // NSDateComponents *weekdayComponents = [calendar components:NSWeekdayCalendarUnit fromDate:self];
    
    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
    
    // to get the end of week for a particular date, add (7 – weekday) days
    
    [componentsToAdd setDay:day];
    
    NSDate *dateAfterDay = [calendar dateByAddingComponents:componentsToAdd toDate:self options:0];
    
    [componentsToAdd release];
    
    return dateAfterDay;
    
}

//month个月后的日期

- (NSDate *)dateafterMonth:(int)month

{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
    
    [componentsToAdd setMonth:month];
    
    NSDate *dateAfterMonth = [calendar dateByAddingComponents:componentsToAdd toDate:self options:0];
    
    [componentsToAdd release];
    
    return dateAfterMonth;
    
}

//获取日

- (NSUInteger)getDay{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *dayComponents = [calendar components:(NSDayCalendarUnit) fromDate:self];
    
    return [dayComponents day];
    
}

//获取月

- (NSUInteger)getMonth

{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *dayComponents = [calendar components:(NSMonthCalendarUnit) fromDate:self];
    
    return [dayComponents month];
    
}

//获取年

- (NSUInteger)getYear

{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *dayComponents = [calendar components:(NSYearCalendarUnit) fromDate:self];
    
    return [dayComponents year];
    
}

//获取小时

- (int )getHour {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSUInteger unitFlags =NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit |NSHourCalendarUnit |NSMinuteCalendarUnit;
    
    NSDateComponents *components = [calendar components:unitFlags fromDate:self];
    
    NSInteger hour = [components hour];
    
    return (int)hour;
    
}

//获取分钟

- (int)getMinute {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSUInteger unitFlags =NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit |NSHourCalendarUnit |NSMinuteCalendarUnit;
    
    NSDateComponents *components = [calendar components:unitFlags fromDate:self];
    
    NSInteger minute = [components minute];
    
    return (int)minute;
    
}

- (int )getHour:(NSDate *)date {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSUInteger unitFlags =NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit |NSHourCalendarUnit |NSMinuteCalendarUnit;
    
    NSDateComponents *components = [calendar components:unitFlags fromDate:date];
    
    NSInteger hour = [components hour];
    
    return (int)hour;
    
}

- (int)getMinute:(NSDate *)date {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSUInteger unitFlags =NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit |NSHourCalendarUnit |NSMinuteCalendarUnit;
    
    NSDateComponents *components = [calendar components:unitFlags fromDate:date];
    
    NSInteger minute = [components minute];
    
    return (int)minute;
    
}

//在当前日期前几天

- (NSUInteger)daysAgo {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *components = [calendar components:(NSDayCalendarUnit)
                                    
                                               fromDate:self
                                    
                                                 toDate:[NSDate date]
                                    
                                                options:0];
    
    return [components day];
    
}

//午夜时间距今几天

- (NSUInteger)daysAgoAgainstMidnight {
    
    // get a midnight version of ourself:
    
    NSDateFormatter *mdf = [[NSDateFormatter alloc] init];
    
    [mdf setDateFormat:@"yyyy-MM-dd"];
    
    NSDate *midnight = [mdf dateFromString:[mdf stringFromDate:self]];
    
    [mdf release];
    
    return (int)[midnight timeIntervalSinceNow] / (60*60*24) *-1;
    
}

- (NSString *)stringDaysAgo {
    
    return [self stringDaysAgoAgainstMidnight:YES];
    
}

- (NSString *)stringDaysAgoAgainstMidnight:(BOOL)flag {
    
    NSUInteger daysAgo = (flag) ? [self daysAgoAgainstMidnight] : [self daysAgo];
    
    NSString *text = nil;
    
    switch (daysAgo) {
            
        case 0:
            
            text = @"Today";
            
            break;
            
        case 1:
            
            text = @"Yesterday";
            
            break;
            
        default:
            
            text = [NSString stringWithFormat:@"%d days ago", daysAgo];
            
    }
    
    return text;
    
}

-(double)RFC822TimeInteral{
    
    NSCalendar* calendar = [NSCalendar currentCalendar];
    NSDateComponents* component = [[NSDateComponents alloc] init];
    [component setYear:-31];    
    NSDate* date = [calendar dateByAddingComponents:component toDate:self options:0];
    DebugLog(@"date is %@", [date description]);
    DebugLog(@"year is %i, month is %i, day is %i", [date getYear], [date getMonth], [date getDay]);    
    [component release];
    
    return [date timeIntervalSince1970];
}

//返回一周的第几天(周末为第一天)

- (NSUInteger)weekday {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *weekdayComponents = [calendar components:(NSWeekdayCalendarUnit) fromDate:self];
    
    return [weekdayComponents weekday];
    
}

//转为NSString类型的

+ (NSDate *)dateFromString:(NSString *)string {
    
    return [NSDate dateFromString:string withFormat:[NSDate dbFormatString]];
    
}

+ (NSDate *)dateFromString:(NSString *)string withFormat:(NSString *)format {
    
    NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
    
    [inputFormatter setDateFormat:format];
    
    NSDate *date = [inputFormatter dateFromString:string];
    
    [inputFormatter release];
    
    return date;
    
}

+ (NSString *)stringFromDate:(NSDate *)date withFormat:(NSString *)format {
    
    return [date stringWithFormat:format];
    
}

+ (NSString *)stringFromDate:(NSDate *)date {
    
    return [date string];
    
}

+ (NSString *)stringForDisplayFromDate:(NSDate *)date prefixed:(BOOL)prefixed {
    
    /*
     
     * if the date is in today, display 12-hour time with meridian,
     
     * if it is within the last 7 days, display weekday name (Friday)
     
     * if within the calendar year, display as Jan 23
     
     * else display as Nov 11, 2008
     
     */
    
    NSDate *today = [NSDate date];
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDateComponents *offsetComponents = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
                                          
                                                     fromDate:today];
    
    NSDate *midnight = [calendar dateFromComponents:offsetComponents];
    
    NSDateFormatter *displayFormatter = [[NSDateFormatter alloc] init];
    
    NSString *displayString = nil;
    
    // comparing against midnight
    
    if ([date compare:midnight] == NSOrderedDescending) {
        
        if (prefixed) {
            
            [displayFormatter setDateFormat:@"'at' h:mm a"]; // at 11:30 am
            
        } else {
            
            [displayFormatter setDateFormat:@"h:mm a"]; // 11:30 am
            
        }
        
    } else {
        
        // check if date is within last 7 days
        
        NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
        
        [componentsToSubtract setDay:-7];
        
        NSDate *lastweek = [calendar dateByAddingComponents:componentsToSubtract toDate:today options:0];
        
        [componentsToSubtract release];
        
        if ([date compare:lastweek] == NSOrderedDescending) {
            
            [displayFormatter setDateFormat:@"EEEE"]; // Tuesday
            
        } else {
            
            // check if same calendar year
            
            NSInteger thisYear = [offsetComponents year];
            
            NSDateComponents *dateComponents = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
                                                
                                                           fromDate:date];
            
            NSInteger thatYear = [dateComponents year];
            
            if (thatYear >= thisYear) {
                
                [displayFormatter setDateFormat:@"MMM d"];
                
            } else {
                
                [displayFormatter setDateFormat:@"MMM d, yyyy"];
                
            }
            
        }
        
        if (prefixed) {
            
            NSString *dateFormat = [displayFormatter dateFormat];
            
            NSString *prefix = @"‘on’ ";
            
            [displayFormatter setDateFormat:[prefix stringByAppendingString:dateFormat]];
            
        }
        
    }
    
    // use display formatter to return formatted date string
    
    displayString = [displayFormatter stringFromDate:date];
    
    [displayFormatter release];
    
    return displayString;
    
}

+ (NSString *)stringForDisplayFromDate:(NSDate *)date {
    
    return [self stringForDisplayFromDate:date prefixed:NO];
    
}

- (NSString *)stringWithFormat:(NSString *)format {
    
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
    
    [outputFormatter setDateFormat:format];
    
    NSString *timestamp_str = [outputFormatter stringFromDate:self];
    
    [outputFormatter release];
    
    return timestamp_str;
    
}

- (NSString *)string {
    
    return [self stringWithFormat:[NSDate dbFormatString]];
    
}

- (NSString *)stringWithDateStyle:(NSDateFormatterStyle)dateStyle timeStyle:(NSDateFormatterStyle)timeStyle {
    
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
    
    [outputFormatter setDateStyle:dateStyle];
    
    [outputFormatter setTimeStyle:timeStyle];
    
    NSString *outputString = [outputFormatter stringFromDate:self];
    
    [outputFormatter release];
    
    return outputString;
    
}

//返回周日的的开始时间

- (NSDate *)beginningOfWeek {
    
    // largely borrowed from "Date and Time Programming Guide for Cocoa"
    
    // we’ll use the default calendar and hope for the best
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSDate *beginningOfWeek = nil;
    
    BOOL ok = [calendar rangeOfUnit:NSWeekCalendarUnit startDate:&beginningOfWeek
               
                           interval:NULL forDate:self];
    
    if (ok) {
        
        return beginningOfWeek;
        
    }
    
    // couldn’t calc via range, so try to grab Sunday, assuming gregorian style
    
    // Get the weekday component of the current date
    
    NSDateComponents *weekdayComponents = [calendar components:NSWeekdayCalendarUnit fromDate:self];
    
    /*
     
     Create a date components to represent the number of days to subtract from the current date.
     
     The weekday value for Sunday in the Gregorian calendar is 1, so subtract 1 from the number of days to subtract from the date in question.  (If today’s Sunday, subtract 0 days.)
     
     */
    
    NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
    
    [componentsToSubtract setDay: 0 - ([weekdayComponents weekday] - 1)];
    
    beginningOfWeek = nil;
    
    beginningOfWeek = [calendar dateByAddingComponents:componentsToSubtract toDate:self options:0];
    
    [componentsToSubtract release];
    
    //normalize to midnight, extract the year, month, and day components and create a new date from those components.
    
    NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
                                    
                                               fromDate:beginningOfWeek];
    
    return [calendar dateFromComponents:components];
    
}

//返回当前天的年月日.

- (NSDate *)beginningOfDay {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    // Get the weekday component of the current date
    
    NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
                                    
                                               fromDate:self];
    
    return [calendar dateFromComponents:components];
    
}

//返回该月的第一天

- (NSDate *)beginningOfMonth

{
    return [[self dateAfterDay:-[self getDay] + 1] beginningOfDay];
    
}

//该月的最后一天

- (NSDate *)endOfMonth

{
    
    return [[[[self beginningOfMonth] dateafterMonth:1] dateAfterDay:-1] beginningOfDay];
    
}

//返回当前周的周末

- (NSDate *)endOfWeek {
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    // Get the weekday component of the current date
    
    NSDateComponents *weekdayComponents = [calendar components:NSWeekdayCalendarUnit fromDate:self];
    
    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
    
    // to get the end of week for a particular date, add (7 – weekday) days
    
    [componentsToAdd setDay:(7 - [weekdayComponents weekday])];
    
    NSDate *endOfWeek = [calendar dateByAddingComponents:componentsToAdd toDate:self options:0];
    
    [componentsToAdd release];
    
    return endOfWeek;
    
}

+ (NSString *)dateFormatString {
    
    return @"yyyy-MM-dd";
    
}

+ (NSString *)timeFormatString {
    
    return @"HH:mm:ss";
    
}

+ (NSString *)timestampFormatString {
    
    return @"yyyy-MM-dd HH:mm:ss";
    
}

// preserving for compatibility

+ (NSString *)dbFormatString {
    
    return [NSDate timestampFormatString];
    
}

@end