NSDateHelper.m

//
//  NSDateHelper.m
//  Enormego Cocoa Helpers
//
//  Created by Shaun Harrison on 10/15/08.
//  Copyright 2008 enormego. All rights reserved.
//

#import "NSDateHelper.h"

@implementation NSDate (Helper)
+ (NSDate*)dateFromOffSetDays:(NSInteger)offset;
{
	NSDate* yourDate = [NSDate new];
	NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *todayComponents = [gregorian components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:yourDate];
    NSInteger theDay = [todayComponents day];
    NSInteger theMonth = [todayComponents month];
    NSInteger theYear = [todayComponents year];
	
    // now build a NSDate object for yourDate using these components
    NSDateComponents *components = [[NSDateComponents alloc] init];
    [components setDay:theDay]; 
    [components setMonth:theMonth]; 
    [components setYear:theYear];
    NSDate *thisDate = [gregorian dateFromComponents:components];
    [components release];
	
    // now build a NSDate object for the next day
    NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
    [offsetComponents setDay:offset];
    NSDate *nextDate = [gregorian dateByAddingComponents:offsetComponents toDate: yourDate options:0];
    [offsetComponents release];
    [gregorian release];
    
	return nextDate;
}



+ (NSDate*)dateWithString:(NSString*)dateString formatString:(NSString*)dateFormatterString {
	if(!dateString) return nil;
	
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
	[formatter setDateFormat:dateFormatterString];
	return [formatter dateFromString:dateString];
}

+ (NSDate*)dateWithISO8601String:(NSString*)dateString {
	if(!dateString) return nil;
	if([dateString hasSuffix:@" 00:00"]) {
		dateString = [[dateString substringToIndex:(dateString.length-6)] stringByAppendingString:@"GMT"];
	} else if ([dateString hasSuffix:@"Z"]) {
		dateString = [[dateString substringToIndex:(dateString.length-1)] stringByAppendingString:@"GMT"];
	}
	
	return [[self class] dateWithString:dateString formatString:@"yyyy-MM-ddTHH:mm:ssZZZ"];
}

+ (NSDate*)dateWithDateString:(NSString*)dateString {
	return [[self class] dateWithString:dateString formatString:@"yyyy-MM-dd"];
}

+ (NSDate*)dateWithDateTimeString:(NSString*)dateString {
	return [[self class] dateWithString:dateString formatString:@"yyyy-MM-dd HH:mm:ss"];
}

+ (NSDate*)dateWithLongDateTimeString:(NSString*)dateString {
	return [[self class] dateWithString:dateString formatString:@"dd MMM yyyy HH:mm:ss"];
}

+ (NSDate*)dateWithRSSDateString:(NSString*)dateString {
	if ([dateString hasSuffix:@"Z"]) {
		dateString = [[dateString substringToIndex:(dateString.length-1)] stringByAppendingString:@"GMT"];
	}
	
	return [[self class] dateWithString:dateString formatString:@"EEE, d MMM yyyy HH:mm:ss ZZZ"];
}

+ (NSDate*)dateWithAltRSSDateString:(NSString*)dateString {
	if ([dateString hasSuffix:@"Z"]) {
		dateString = [[dateString substringToIndex:(dateString.length-1)] stringByAppendingString:@"GMT"];
	}
	
	return [[self class] dateWithString:dateString formatString:@"d MMM yyyy HH:mm:ss ZZZ"];
}

- (NSString*)formattedDateWithFormatString:(NSString*)dateFormatterString {
	if(!dateFormatterString) return nil;
	
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
	[formatter setDateFormat:dateFormatterString];
	[formatter setAMSymbol:@"am"];
	[formatter setPMSymbol:@"pm"];
	return [formatter stringFromDate:self];
}

- (NSString*)formattedDate {
	return [self formattedDateWithFormatString:@"EEE, d MMM 'at' h:mma"];
}

- (NSString*)relativeFormattedDate {
    // Initialize the formatter.
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
    [formatter setDateStyle:NSDateFormatterShortStyle];
    [formatter setTimeStyle:NSDateFormatterNoStyle];
	
    // Initialize the calendar and flags.
    unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSWeekdayCalendarUnit;
    NSCalendar* calendar = [NSCalendar currentCalendar];
	
    // Create reference date for supplied date.
    NSDateComponents *comps = [calendar components:unitFlags fromDate:self];
    [comps setHour:0];
    [comps setMinute:0];
    [comps setSecond:0];
	
    NSDate* suppliedDate = [calendar dateFromComponents:comps];
	
    // Iterate through the eight days (tomorrow, today, and the last six).
    int i;
    for (i = -1; i < 7; i++) {
        // Initialize reference date.
        comps = [calendar components:unitFlags fromDate:[NSDate date]];
        [comps setHour:0];
        [comps setMinute:0];
        [comps setSecond:0];
        [comps setDay:[comps day] - i];
        NSDate* referenceDate = [calendar dateFromComponents:comps];
        // Get week day (starts at 1).
        int weekday = [[calendar components:unitFlags fromDate:referenceDate] weekday] - 1;
		
        if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 0) {
            // Today
			[formatter setDateStyle:NSDateFormatterNoStyle];
			[formatter setTimeStyle:NSDateFormatterShortStyle];
			break;
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 1) {
            // Yesterday
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return @"Yesterday";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame) {
            // Day of the week
            return [[formatter weekdaySymbols] objectAtIndex:weekday];
        }
    }
	
    // It's not in those eight days.
    return [formatter stringFromDate:self];	
}

- (NSString*)relativeFormattedDateOnly {
    // Initialize the formatter.
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
    [formatter setDateStyle:NSDateFormatterShortStyle];
    [formatter setTimeStyle:NSDateFormatterNoStyle];
	
    // Initialize the calendar and flags.
    unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSWeekdayCalendarUnit;
    NSCalendar* calendar = [NSCalendar currentCalendar];
	
    // Create reference date for supplied date.
    NSDateComponents *comps = [calendar components:unitFlags fromDate:self];
    [comps setHour:0];
    [comps setMinute:0];
    [comps setSecond:0];
	
    NSDate* suppliedDate = [calendar dateFromComponents:comps];
	
    // Iterate through the eight days (tomorrow, today, and the last six).
    int i;
    for (i = -1; i < 7; i++) {
        // Initialize reference date.
        comps = [calendar components:unitFlags fromDate:[NSDate date]];
        [comps setHour:0];
        [comps setMinute:0];
        [comps setSecond:0];
        [comps setDay:[comps day] - i];
        NSDate* referenceDate = [calendar dateFromComponents:comps];
        // Get week day (starts at 1).
        int weekday = [[calendar components:unitFlags fromDate:referenceDate] weekday] - 1;
		
        if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 0) {
            // Today
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return @"Today";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 1) {
            // Yesterday
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return @"Yesterday";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == -1) {
            // Yesterday
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return@"Tomorrow";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame) {
            // Day of the week
            return [[formatter weekdaySymbols] objectAtIndex:weekday];
        }
    }
	
    // It's not in those eight days.
    return [formatter stringFromDate:self];	
}

- (NSString*)relativeFormattedDateTime {
    // Initialize the formatter.
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
    [formatter setDateStyle:NSDateFormatterShortStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
	[formatter setAMSymbol:@"am"];
	[formatter setPMSymbol:@"pm"];
	
    // Initialize the calendar and flags.
    unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSWeekdayCalendarUnit;
    NSCalendar* calendar = [NSCalendar currentCalendar];
	
    // Create reference date for supplied date.
    NSDateComponents *comps = [calendar components:unitFlags fromDate:self];
    [comps setHour:0];
    [comps setMinute:0];
    [comps setSecond:0];
	
    NSDate* suppliedDate = [calendar dateFromComponents:comps];
	
    // Iterate through the eight days (tomorrow, today, and the last six).
    int i;
    for (i = -1; i < 7; i++) {
        // Initialize reference date.
        comps = [calendar components:unitFlags fromDate:[NSDate date]];
        [comps setHour:0];
        [comps setMinute:0];
        [comps setSecond:0];
        [comps setDay:[comps day] - i];
        NSDate* referenceDate = [calendar dateFromComponents:comps];
        // Get week day (starts at 1).
        int weekday = [[calendar components:unitFlags fromDate:referenceDate] weekday] - 1;
		
        if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 0) {
            // Today
            [formatter setDateStyle:NSDateFormatterNoStyle];
  			return [NSString stringWithFormat:@"Today, %@", [formatter stringFromDate:self]];
		} else if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 1) {
            // Yesterday
            [formatter setDateStyle:NSDateFormatterNoStyle];
			return [NSString stringWithFormat:@"Yesterday, %@", [formatter stringFromDate:self]];
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame) {
            // Day of the week
            NSString* day = [[formatter weekdaySymbols] objectAtIndex:weekday];
			[formatter setDateStyle:NSDateFormatterNoStyle];
			return [NSString stringWithFormat:@"%@, %@", day, [formatter stringFromDate:self]];
        }
    }
	
    // It's not in those eight days.
    [formatter setDateStyle:NSDateFormatterShortStyle];
    [formatter setTimeStyle:NSDateFormatterNoStyle];
	NSString* date = [formatter stringFromDate:self];
	
    [formatter setDateStyle:NSDateFormatterNoStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
	NSString* time = [formatter stringFromDate:self];
	
	return [NSString stringWithFormat:@"%@, %@", date, time];
}

- (NSString*)relativeLongFormattedDate {
    // Initialize the formatter.
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
    [formatter setDateStyle:NSDateFormatterFullStyle];
    [formatter setTimeStyle:NSDateFormatterNoStyle];
	
    // Initialize the calendar and flags.
    unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSWeekdayCalendarUnit;
    NSCalendar* calendar = [NSCalendar currentCalendar];
	
    // Create reference date for supplied date.
    NSDateComponents *comps = [calendar components:unitFlags fromDate:self];
    [comps setHour:0];
    [comps setMinute:0];
    [comps setSecond:0];
	
    NSDate* suppliedDate = [calendar dateFromComponents:comps];
	
    // Iterate through the eight days (tomorrow, today, and the last six).
    int i;
    for (i = -1; i < 7; i++) {
        // Initialize reference date.
        comps = [calendar components:unitFlags fromDate:[NSDate date]];
        [comps setHour:0];
        [comps setMinute:0];
        [comps setSecond:0];
        [comps setDay:[comps day] - i];
        NSDate* referenceDate = [calendar dateFromComponents:comps];
        // Get week day (starts at 1).
        int weekday = [[calendar components:unitFlags fromDate:referenceDate] weekday] - 1;
		
        if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 0) {
            // Today
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return @"Today";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == 1) {
            // Yesterday
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return @"Yesterday";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame && i == -1) {
            // Tomorrow
            [formatter setDateStyle:NSDateFormatterNoStyle];
            return @"Tomorrow";
        } else if ([suppliedDate compare:referenceDate] == NSOrderedSame) {
            // Day of the week
            return [[formatter weekdaySymbols] objectAtIndex:weekday];
        }
    }
	
    // It's not in those eight days.
    return [formatter stringFromDate:self];	
}

- (NSString*)formattedTime {
    // Initialize the formatter.
    NSDateFormatter* formatter = [[[NSDateFormatter alloc] init] autorelease];
    [formatter setDateStyle:NSDateFormatterNoStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
	
    return [formatter stringFromDate:self];	
}

- (NSString*)iso8601Formatted {
	return [self formattedDateWithFormatString:@"yyyy-MM-dd'T'HH:mm:ssZ"];
}

- (BOOL)isPastDate {
	NSDate* now = [NSDate date];
	if([[now earlierDate:self] isEqualToDate:self]) {
		return YES;
	} else {
		return NO;
	}	
}

-(NSDate*) dateOnly{
	// start by retrieving day, weekday, month and year components for today
	NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
	NSDateComponents *todayComponents = [gregorian components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:self];
	NSInteger theDay = [todayComponents day];
	NSInteger theMonth = [todayComponents month];
	NSInteger theYear = [todayComponents year];
	
	// now build a NSDate object for the input date using these components
	NSDateComponents *components = [[NSDateComponents alloc] init];
	[components setDay:theDay]; 
	[components setMonth:theMonth]; 
	[components setYear:theYear];
	NSDate *thisDate = [gregorian dateFromComponents:components];
	[components release];
	return thisDate;
}

@end