[ACCEPTED]-NSDictionary with ordered keys-nsdictionary

Accepted answer
Score: 23

The solution of having an associated NSMutableArray 4 of keys isn't so bad. It avoids subclassing 3 NSDictionary, and if you are careful with 2 writing accessors, it shouldn't be too hard 1 to keep synchronised.

Score: 21

I'm late to the game with an actual answer, but 8 you might be interested to investigate CHOrderedDictionary. It's 7 a subclass of NSMutableDictionary which 6 encapsulates another structure for maintaining 5 key ordering. (It's part of CHDataStructures.framework.) I find it 4 to be more convenient than managing a dictionary 3 and array separately.

Disclosure: This is 2 open-source code which I wrote. Just hoping 1 it may be useful to others facing this problem.

Score: 14

There is no such inbuilt method from which 8 you can acquire this. But a simple logic 7 work for you. You can simply add few numeric 6 text in front of each key while you prepare 5 the dictionary. Like

NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:
                       @"02.Being Assigned",@"bea",
                       @"06.En Route",@"inr",
                       @"07.On Job Site",@"ojs",
                       @"08.In Progress",@"inp",
                       @"09.On Hold",@"onh",
                       @"12.Cancelled", @"can",

Now if you can use sortingArrayUsingSelector 4 while getting all keys in the same order 3 as you place.

NSArray *arr =  [[dict allKeys] sortedArrayUsingSelector:@selector(localizedStandardCompare:)];

At the place where you want 2 to display keys in UIView, just chop off 1 the front 3 character.

Score: 8

If you're going to subclass NSDictionary 12 you need to implement these methods as a 11 minimum:

  • NSDictionary
    • -count
    • -objectForKey:
    • -keyEnumerator
  • NSMutableDictionary
    • -removeObjectForKey:
    • -setObject:forKey:
  • NSCopying/NSMutableCopying
    • -copyWithZone:
    • -mutableCopyWithZone:
  • NSCoding
    • -encodeWithCoder:
    • -initWithCoder:
  • NSFastEnumeration (for Leopard)
    • -countByEnumeratingWithState:objects:count:

The easiest way to do what you want 10 is to make a subclass of NSMutableDictionary 9 that contains its' own NSMutableDictionary 8 that it manipulates and an NSMutableArray 7 to store an ordered set of keys.

If you're 6 never going to encode your objects you could 5 conceivable skip implementing -encodeWithCoder: and -initWithCoder:

All of 4 your method implementations in the 10 methods 3 above would then either go directly through 2 your hosted dictionary or your ordered key 1 array.

Score: 5

My little addition: sorting by numeric key 1 (Using shorthand notations for smaller code)

// the resorted result array
NSMutableArray *result = [NSMutableArray new];
// the source dictionary - keys may be Ux timestamps (as integer, wrapped in NSNumber)
NSDictionary *dict =
  @0: @"a",
  @3: @"d",
  @1: @"b",
  @2: @"c"

{// do the sorting to result
    NSArray *arr = [[dict allKeys] sortedArrayUsingSelector:@selector(compare:)];

    for (NSNumber *n in arr)
        [result addObject:dict[n]];
Score: 3

Quick 'n dirty:

When you need to order your 7 dictionary (herein called “myDict”), do 6 this:

     NSArray *ordering = [NSArray arrayWithObjects: @"Thing",@"OtherThing",@"Last Thing",nil];

Then, when you need to order your dictionary, create 5 an index:

    NSEnumerator *sectEnum = [ordering objectEnumerator];
    NSMutableArray *index = [[NSMutableArray alloc] init];
        id sKey;
        while((sKey = [sectEnum nextObject])) {
            if ([myDict objectForKey:sKey] != nil ) {
                [index addObject:sKey];

Now, the *index object will contain 4 the appropriate keys in the correct order. Note 3 that this solution does not require that 2 all the keys necessarily exist, which is 1 the usual situation we're dealing with...

Score: 3

Minimal implementation of an ordered subclass 2 of NSDictionary (based on https://github.com/nicklockwood/OrderedDictionary). Feel free to 1 extend for your needs:

Swift 3 and 4

class MutableOrderedDictionary: NSDictionary {
    let _values: NSMutableArray = []
    let _keys: NSMutableOrderedSet = []

    override var count: Int {
        return _keys.count
    override func keyEnumerator() -> NSEnumerator {
        return _keys.objectEnumerator()
    override func object(forKey aKey: Any) -> Any? {
        let index = _keys.index(of: aKey)
        if index != NSNotFound {
            return _values[index]
        return nil
    func setObject(_ anObject: Any, forKey aKey: String) {
        let index = _keys.index(of: aKey)
        if index != NSNotFound {
            _values[index] = anObject
        } else {


let normalDic = ["hello": "world", "foo": "bar"]
// initializing empty ordered dictionary
let orderedDic = MutableOrderedDictionary()
// copying normalDic in orderedDic after a sort
normalDic.sorted { $0.0.compare($1.0) == .orderedAscending }
         .forEach { orderedDic.setObject($0.value, forKey: $0.key) }
// from now, looping on orderedDic will be done in the alphabetical order of the keys
orderedDic.forEach { print($0) }


@interface MutableOrderedDictionary<__covariant KeyType, __covariant ObjectType> : NSDictionary<KeyType, ObjectType>
@implementation MutableOrderedDictionary
    NSMutableArray *_values;
    NSMutableOrderedSet *_keys;

- (instancetype)init
    if ((self = [super init]))
        _values = NSMutableArray.new;
        _keys = NSMutableOrderedSet.new;
    return self;

- (NSUInteger)count
    return _keys.count;

- (NSEnumerator *)keyEnumerator
    return _keys.objectEnumerator;

- (id)objectForKey:(id)key
    NSUInteger index = [_keys indexOfObject:key];
    if (index != NSNotFound)
        return _values[index];
    return nil;

- (void)setObject:(id)object forKey:(id)key
    NSUInteger index = [_keys indexOfObject:key];
    if (index != NSNotFound)
        _values[index] = object;
        [_keys addObject:key];
        [_values addObject:object];


NSDictionary *normalDic = @{@"hello": @"world", @"foo": @"bar"};
// initializing empty ordered dictionary
MutableOrderedDictionary *orderedDic = MutableOrderedDictionary.new;
// copying normalDic in orderedDic after a sort
for (id key in [normalDic.allKeys sortedArrayUsingSelector:@selector(compare:)]) {
    [orderedDic setObject:normalDic[key] forKey:key];
// from now, looping on orderedDic will be done in the alphabetical order of the keys
for (id key in orderedDic) {
    NSLog(@"%@:%@", key, orderedDic[key]);
Score: 2

For, Swift 3. Please try out the following approach

        //Sample Dictionary
        let dict: [String: String] = ["01.One": "One",
                                      "02.Two": "Two",
                                      "03.Three": "Three",
                                      "04.Four": "Four",
                                      "05.Five": "Five",
                                      "06.Six": "Six",
                                      "07.Seven": "Seven",
                                      "08.Eight": "Eight",
                                      "09.Nine": "Nine",
                                      "10.Ten": "Ten"

        //Print the all keys of dictionary

        //Sort the dictionary keys array in ascending order
        let sortedKeys = dict.keys.sorted { $0.localizedCaseInsensitiveCompare($1) == ComparisonResult.orderedAscending }

        //Print the ordered dictionary keys

        //Get the first ordered key
        var firstSortedKeyOfDictionary = sortedKeys[0]

        // Get range of all characters past the first 3.
        let c = firstSortedKeyOfDictionary.characters
        let range = c.index(c.startIndex, offsetBy: 3)..<c.endIndex

        // Get the dictionary key by removing first 3 chars
        let firstKey = firstSortedKeyOfDictionary[range]

        //Print the first key


Score: 0

I don’t like C++ very much, but one solution 14 that I see myself using more and more is 13 to use Objective-C++ and std::map from the Standard 12 Template Library. It is a dictionary whose 11 keys are automatically sorted on insertion. It 10 works surprisingly well with either scalar 9 types or Objective-C objects both as keys 8 and as values.

If you need to include an 7 array as a value, just use std::vector instead of NSArray.

One 6 caveat is that you might want to provide 5 your own insert_or_assign function, unless you can use C++17 4 (see this answer). Also, you need to typedef your types to 3 prevent certain build errors. Once you figure 2 out how to use std::map, iterators etc., it is pretty 1 straightforward and fast.

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