Flatten NSDictionary using Associated References http://www.restlessthinker.com/blog/programming/flatten-nsdictionary-and-associated-references/

gistfile1.m

#import <Foundation/Foundation.h>

@interface NSDictionary (Flatten)

- (NSMutableArray *)flattenedArray;
  
@end

gistfile2.m

#import "NSDictionary+Flatten.h"
#import <objc/runtime.h>

static char flattenedArrayKey;

@interface NSDictionary (FlattenPrivate)

- (void)flattenWithRecursion:(id)object;
- (void)enumerate:(id)object depth:(int)depth parent:(id)parent;

@end


@implementation NSDictionary (Flatten)

- (NSMutableArray *)flattenedArray {
  NSMutableArray *initArray = [[NSMutableArray alloc] init];
	objc_setAssociatedObject( self, &flattenedArrayKey, initArray, OBJC_ASSOCIATION_RETAIN );
	[self flattenWithRecursion:self];
	return (NSMutableArray *)objc_getAssociatedObject( self, &flattenedArrayKey );
}

- (void)flattenWithRecursion:(id)object {
	[self enumerate:object depth:0 parent:nil];
}

- (void)enumerate:(id)object depth:(int)depth parent:(id)parent {
	
	if( [object isKindOfClass:[NSDictionary class]] ) {
		
		for( NSString * key in [object allKeys] ) {
			id child = [object objectForKey:key];
			[self enumerate:child depth:depth+1 parent:object];
		}
		
		
	} else if( [object isKindOfClass:[NSArray class]] ) {
		
		for( id child in object ) {
			[self enumerate:child depth:depth+1 parent:object];
		}
		
	} else if( [object isKindOfClass:[NSSet class]] ) {
		
		for( id child in object ) {
			[self enumerate:child depth:depth+1 parent:object];
		}
	}
	else{
		//	not a collection/container it has ended
		//NSLog(@"Node: %@  depth: %d",[object description],depth);
		NSMutableArray *assocObject = (NSMutableArray *)objc_getAssociatedObject(self, &flattenedArrayKey);
		[assocObject addObject:object];
	}
}

@end

gistfile3.m

#import <SenTestingKit/SenTestingKit.h>
#import "NSDictionary+Flatten.h"

@interface NSDictionaryFlattenTests : SenTestCase {
  
}

- (void)testFlatten;

@end

@implementation NSDictionaryFlattenTests


- (void)setUp {
	[super setUp];
}

- (void)tearDown {
	[super tearDown];
}

- (void)testFlatten {
	NSDictionary *collection1 = @{ @"firstName" : @"Foo", @"lastName" : @"Bar", @"middleName" : @"middle" };
	NSArray *collection2 = @[@"134234", @"234323"];
	NSSet *collection3 = [[NSSet alloc] initWithObjects:@"fooset", @"barset", nil];
	
	
	NSDictionary *members = [[NSDictionary alloc] initWithObjectsAndKeys:collection1, @"key1", collection2, @"key2", collection3, @"key3", nil];
	
	NSDate *startTime = [NSDate date];
	NSMutableArray *testArray = [members flattenedArray];
	NSDate *endTime = [NSDate date];
	
	NSTimeInterval executionTime = [endTime timeIntervalSinceDate:startTime];
	NSLog(@"execution took approx: %2f seconds", executionTime );
	
	STAssertTrue( [testArray count] == 7, @"should be equal");
}


@end