NSDate+Surrounding.h

//
//  NSDate+Surrounding.h
//
//  Created by Josh Kendall on 12/22/10.
//  Copyright 2010 JoshuaKendall.com. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSDate (Surrounding)

- (NSDate *)dateSinceToday:(int)days;
- (NSDate *)yesterday;
- (NSDate *)tomorrow;

@end

NSDate+Surrounding.m

//
//  NSDate+Surrounding.m
//
//  Created by Josh Kendall on 12/22/10.
//  Copyright 2010 JoshuaKendall.com. All rights reserved.
//

#import "NSDate+Surrounding.h"

@implementation NSDate (Surrounding)

- (NSDate *)dateSinceToday:(int)days {
    NSDate *date = [NSDate date];
    NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
    [components setDay:days];
    NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
    return [gregorian dateByAddingComponents:components toDate:date options:0];
}

- (NSDate *)yesterday {
    return [self dateSinceToday: -1];
}

- (NSDate *)tomorrow {
    return [self dateSinceToday: 1];
}

@end