LNOrderedMutableDictionary.h

//
// Created by Liam Nichols on 14/10/2013.
// Copyright (c) 2013 Mubaloo Ltd. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface LNOrderedMutableDictionary : NSMutableDictionary

///If `anObject` is nil, it will not be added to the dictionary.
- (void)setNothingIfNil:(id)anObject forKey:(id)aKey;

@end

LNOrderedMutableDictionary.m

//
// Created by Liam Nichols on 14/10/2013.
// Copyright (c) 2013 Mubaloo Ltd. All rights reserved.
//


#import "LNOrderedMutableDictionary.h"

@interface LNOrderedMutableDictionary ()

@property (nonatomic, strong) NSMutableDictionary *dictionary;
@property (nonatomic, strong) NSMutableOrderedSet *array;

@end

@implementation LNOrderedMutableDictionary

- (id)initWithCapacity:(NSUInteger)capacity
{
    self = [super init];
    if (self != nil)
    {
        self.dictionary = [[NSMutableDictionary alloc] initWithCapacity:capacity];
        self.array = [[NSMutableOrderedSet alloc] initWithCapacity:capacity];
    }
    return self;
}

- (id)init
{
    self = [self initWithCapacity:0];
    if (self)
    {

    }
    return self;
}

- (void)setObject:(id)anObject forKey:(id)aKey
{
    [self.array removeObject:aKey];
    [self.array addObject:aKey];
    [self.dictionary setObject:anObject forKey:aKey];
}

- (void)setNothingIfNil:(id)anObject forKey:(id)aKey
{
    if (anObject != nil)
        [self setObject:anObject forKey:aKey];
}

- (void)removeObjectForKey:(id)aKey
{
    [self.dictionary removeObjectForKey:aKey];
    [self.array removeObject:aKey];
}

- (NSUInteger)count
{
    return [self.dictionary count];
}

- (id)objectForKey:(id)aKey
{
    return [self.dictionary objectForKey:aKey];
}

- (NSEnumerator *)keyEnumerator
{
    return [self.array objectEnumerator];
}

@end