// NSDate+Helper.h
#import <Foundation/Foundation.h>
@interface NSDate (Helper)
- (NSUInteger)daysAgo;
- (NSUInteger)daysAgoAgainstMidnight;
- (NSString *)stringDaysAgo;
- (NSString *)stringDaysAgoAgainstMidnight:(BOOL)flag;
- (NSUInteger)weekday;
+ (NSDate *)dateFromString:(NSString *)string;
+ (NSDate *)dateFromString:(NSString *)string withFormat:(NSString *)format;
+ (NSString *)stringFromDate:(NSDate *)date withFormat:(NSString *)string;
+ (NSString *)stringFromDate:(NSDate *)date;
+ (NSString *)stringForDisplayFromDate:(NSDate *)date;
+ (NSString *)stringForDisplayFromDate:(NSDate *)date prefixed:(BOOL)prefixed;
+ (NSString *)stringForDisplayFromDate:(NSDate *)date prefixed:(BOOL)prefixed alwaysDisplayTime:(BOOL)displayTime;
- (NSString *)string;
- (NSString *)stringWithFormat:(NSString *)format;
- (NSString *)stringWithDateStyle:(NSDateFormatterStyle)dateStyle timeStyle:(NSDateFormatterStyle)timeStyle;
- (NSDate *)beginningOfWeek;
- (NSDate *)beginningOfDay;
- (NSDate *)endOfWeek;
+ (NSString *)dateFormatString;
+ (NSString *)timeFormatString;
+ (NSString *)timestampFormatString;
+ (NSString *)dbFormatString;
@end
#import "NSDate+Helper.h"
@implementation NSDate (Helper)
/*
* This guy can be a little unreliable and produce unexpected results,
* you're better off using daysAgoAgainstMidnight
*/
- (NSUInteger)daysAgo {
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSDayCalendarUnit)
fromDate:self
toDate:[NSDate date]
options:0];
return [components day];
}
- (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;
}
- (NSUInteger)weekday {
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *weekdayComponents = [calendar components:(NSWeekdayCalendarUnit) fromDate:self];
return [weekdayComponents weekday];
}
+ (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 alwaysDisplayTime:(BOOL)displayTime {
/*
* 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
*/
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateFormatter *displayFormatter = [[NSDateFormatter alloc] init];
NSDate *today = [NSDate date];
NSDateComponents *offsetComponents = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
fromDate:today];
NSDate *midnight = [calendar dateFromComponents:offsetComponents];
NSString *displayString = nil;
// comparing against midnight
NSComparisonResult midnight_result = [date compare:midnight];
if (midnight_result == 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];
NSComparisonResult lastweek_result = [date compare:lastweek];
if (lastweek_result == NSOrderedDescending) {
if (displayTime) {
[displayFormatter setDateFormat:@"EEEE h:mm a"];
} else {
[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) {
if (displayTime) {
[displayFormatter setDateFormat:@"MMM d h:mm a"];
}
else {
[displayFormatter setDateFormat:@"MMM d"];
}
} else {
if (displayTime) {
[displayFormatter setDateFormat:@"MMM d, yyyy h:mm a"];
}
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 prefixed:(BOOL)prefixed {
return [[self class] stringForDisplayFromDate:date prefixed:prefixed alwaysDisplayTime:NO];
}
+ (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;
}
- (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];
}
- (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];
}
- (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
