Deep combine NSDictionaries

I added this to the code mentioned above. It may not be fully correct, but it handles the case where 2 dict has an element that 1 dict does not.

+ (NSDictionary *) dictionaryByMerging: (NSDictionary *) dict1 with: (NSDictionary *) dict2 {
    NSMutableDictionary * result = [NSMutableDictionary dictionaryWithDictionary:dict1];
    NSMutableDictionary * resultTemp = [NSMutableDictionary dictionaryWithDictionary:dict1];

    [resultTemp addEntriesFromDictionary:dict2];

    [resultTemp enumerateKeysAndObjectsUsingBlock: ^(id key, id obj, BOOL *stop) {
    if ([dict1 objectForKey:key]) {
        if ([obj isKindOfClass:[NSDictionary class]]) {
            NSDictionary * newVal = [[dict1 objectForKey: key] dictionaryByMergingWith: (NSDictionary *) obj];
            [result setObject: newVal forKey: key];
        } else {
            [result setObject: obj forKey: key];
        }
    }
    else if([dict2 objectForKey:key])
    {
        if ([obj isKindOfClass:[NSDictionary class]]) {
            NSDictionary * newVal = [[dict2 objectForKey: key] dictionaryByMergingWith: (NSDictionary *) obj];
            [result setObject: newVal forKey: key];
        } else {
            [result setObject: obj forKey: key];
        }
    }
}];

return (NSDictionary *) [[result mutableCopy] autorelease];

}

I think this is what you're looking for:

First, you need to make a deep mutable copy, so you can create a category on NSDictionary to do this:

@implementation NSDictionary (DeepCopy)

- (id)deepMutableCopy
{
    id copy(id obj) {
        id temp = [obj mutableCopy];
        if ([temp isKindOfClass:[NSArray class]]) {
            for (int i = 0 ; i < [temp count]; i++) {
               id copied = [copy([temp objectAtIndex:i]) autorelease];
               [temp replaceObjectAtIndex:i withObject:copied];
            }
        } else if ([temp isKindOfClass:[NSDictionary class]]) {
            NSEnumerator *enumerator = [temp keyEnumerator];
            NSString *nextKey;
            while (nextKey = [enumerator nextObject])
                [temp setObject:[copy([temp objectForKey:nextKey]) autorelease]
                         forKey:nextKey];
        } 
        return temp;
    }

    return (copy(self));
}

@end

Then, you can call deepMutableCopy like this:

NSMutableDictionary *someDictionary = [someDict deepMutableCopy];
[someDictionary addEntriesFromDictionary:otherDictionary];

I came here looking for a copy of jQuery's extend but I ended up writing my own implementation. It's a super simple implementation, I did it so I'd understand a way to do it.

+(NSDictionary*) dictionaryByExtending:(NSDictionary*)baseDictionary WithDictionary:(NSDictionary*)extensionDictionary {

    NSMutableDictionary * resultDictionary = [NSMutableDictionary dictionaryWithDictionary:baseDictionary];

    [extensionDictionary enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {

        BOOL isDict = [obj isKindOfClass:[NSDictionary class]];
        BOOL hasValue = [baseDictionary hasObjectForKey:key] != nil;

        id setObj = obj;

        if( hasValue && isDict ) {

            BOOL hasDict = [[baseDictionary objectForKey:key] isKindOfClass:[NSDictionary class]];

            if( hasDict ) {

                NSDictionary * extendedChildDictionary = [NSDictionary dictionaryByExtending:[baseDictionary objectForKey:key] WithDictionary:obj];
                setObj = extendedChildDictionary;

            }

        }

        [resultDictionary setObject:setObj forKey:key];

    }];

    return resultDictionary;

}

-(NSDictionary*) dictionaryByExtendingWithDictionary:(NSDictionary*)extensionDictionary {
    return [NSDictionary dictionaryByExtending:self WithDictionary:extensionDictionary];
}

Hopefully someone will find this helpful, it worked in my tests with deep-recursion. I'm using it to extend deep JSON files full of text.

NSDictionary+Merge.h

#import <Foundation/Foundation.h>

@interface NSDictionary (Merge)

+ (NSDictionary *) dictionaryByMerging: (NSDictionary *) dict1 with: (NSDictionary *) dict2;
- (NSDictionary *) dictionaryByMergingWith: (NSDictionary *) dict;

@end

---

NSDictionary+Merge.m

#import "NSDictionary+Merge.h"

@implementation NSDictionary (Merge)

+ (NSDictionary *) dictionaryByMerging: (NSDictionary *) dict1 with: (NSDictionary *) dict2 {
    NSMutableDictionary * result = [NSMutableDictionary dictionaryWithDictionary:dict1];

[dict2 enumerateKeysAndObjectsUsingBlock: ^(id key, id obj, BOOL *stop) {
    if (![dict1 objectForKey:key]) {
        if ([obj isKindOfClass:[NSDictionary class]]) {
            NSDictionary * newVal = [[dict1 objectForKey: key] dictionaryByMergingWith: (NSDictionary *) obj];
            [result setObject: newVal forKey: key];
        } else {
            [result setObject: obj forKey: key];
        }
    }
}];

    return (NSDictionary *) [[result mutableCopy] autorelease];
}
- (NSDictionary *) dictionaryByMergingWith: (NSDictionary *) dict {
    return [[self class] dictionaryByMerging: self with: dict];
}

@end