An Objective-C data structure that accepts setVariableName: and variableName messages without declaring a variableName property.

example_usage.m

#import "Remap.h"

//to suppress warnings
RemapProperty(sampleText);
RemapProperty(sampleDict);

#define kKey_SampleText	@"sampleTextKey"

int main()
{
	Remap * remap = [[Remap alloc] init];
	[remap setSampleText:@"example"];
	[remap setSampleDict:[NSDictionary dictionaryWithObject:[remap sampleText] forKey:kKey_SampleText]];
	
	NSLog(@"%@", [[remap sampleDict] objectForKey:kKey_SampleText]);

	return 1;
}

Remap.c

//
//  Remap.m
//
//  Created by Adam Wolf on 5/24/10.
//

#import "Remap.h"

@interface Remap ()
@property (nonatomic, retain) 	NSMutableDictionary * _data;
@end

@implementation Remap

@synthesize _data;

- (void) dealloc
{
	relnil(_data);
	[super dealloc];
}

- (id) init
{
	self = [super init];
	if (self != nil) {
		NSMutableDictionary * dict = [[NSMutableDictionary alloc] init];
		[self set_data:dict];
		relnil(dict);
	}
	return self;
}

- (void)forwardInvocation:(NSInvocation *)anInvocation
{
	NSString * selectorName = NSStringFromSelector([anInvocation selector]);
	
	NSRange range = [selectorName rangeOfString:@"set"];
	
	NSInteger numArguments = [[anInvocation methodSignature] numberOfArguments];
	
	if (range.location == 0 && numArguments == 4)
	{
		//setter
		[anInvocation setSelector:@selector(setData:withKey:)];
		[anInvocation setArgument:&selectorName atIndex:3];
		[anInvocation invokeWithTarget:self];
	}
	else if (numArguments == 3)
	{
		[anInvocation setSelector:@selector(getDataWithKey:)];
		[anInvocation setArgument:&selectorName atIndex:2];
		[anInvocation invokeWithTarget:self];
	}


}

- (NSMethodSignature *)	methodSignatureForSelector:(SEL) aSelector
{
	NSString * selectorName = NSStringFromSelector(aSelector);
	
	NSMethodSignature * sig = [super methodSignatureForSelector:aSelector];
	
	if (sig == nil)
	{
		NSRange range = [selectorName rangeOfString:@"set"];
		
		if (range.location == 0)
		{
			sig = [self methodSignatureForSelector:@selector(setData:withKey:)];
		}
		else
		{
			sig = [self methodSignatureForSelector:@selector(getDataWithKey:)];
		}
	}

	return sig;
}
		 
- (NSObject *) getDataWithKey: (NSString *) key
{
	NSObject * returnValue = [[self _data] objectForKey:key];
	return returnValue;
}													   
													   
- (void) setData: (NSObject *) data withKey:(NSString *)key
{
	if (key && [key length] >= 5 && data)
	{
		NSRange range;
		range.length = 1;
		range.location = 3;
		
		NSString * firstChar = [key substringWithRange:range];
		firstChar = [firstChar lowercaseString];
		
		range.length = [key length] - 5; // the 4 we have processed plus the trailing :
		range.location = 4;
		
		NSString * adjustedKey = [NSString stringWithFormat:@"%@%@", firstChar, [key substringWithRange:range]];
		
		[[self _data] setObject:data forKey:adjustedKey];
	}
	else 
	{
		//assert?
	}
}

@end

Remap.h

//
//  Remap.h
//
//  Created by Adam Wolf on 5/24/10.
//
// Meant as a wrapper around NSMutableDictionary to retrieve any arbitrary
// ivar access and store any arbitrary ivar set, regardless of if the ivar is
// define in the object.

#import <Foundation/Foundation.h>

@interface Remap : NSObject {

@private
	NSMutableDictionary * _data;
}

#define RemapProperty(PROP) \
@interface Remap(PROP) \
@property (nonatomic, retain) id PROP; \
@end \
@implementation Remap(PROP) \
@dynamic PROP; \
@end

@end