RestKit/Code/NSDictionary+RKRequestSerialization.m

//
//  NSDictionary+RKRequestSerialization.m
//  RestKit
//
//  Created by Blake Watters on 7/28/09.
//  Copyright 2009 Two Toasters. All rights reserved.
//

#import "NSDictionary+RKRequestSerialization.h"

// private helper function to convert any object to its string representation
static NSString *toString(id object) {
	return [NSString stringWithFormat: @"%@", object];
}

// private helper function to convert string to UTF-8 and URL encode it
static NSString *urlEncode(id object) {
	NSString *string = toString(object);
	return [string stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding];
}


@implementation NSDictionary (RKRequestSerialization)

- (NSString*)URLEncodedString {
	NSMutableArray *parts = [NSMutableArray array];
	for (id key in self) {
		id value = [self objectForKey:key];
		if ([value isKindOfClass:[NSArray class]]) {
			for (id item in value) {
				NSString *part = [NSString stringWithFormat: @"%@[]=%@", 
								  urlEncode(key), urlEncode(item)];
				[parts addObject:part];
			}
		} else {
			NSString *part = [NSString stringWithFormat: @"%@=%@", 
							  urlEncode(key), urlEncode(value)];
			[parts addObject:part];
		}		
	}
	
	return [parts componentsJoinedByString: @"&"];
}

- (NSString*)ContentTypeHTTPHeader {
	return @"application/x-www-form-urlencoded";
}

- (NSData*)HTTPBody {
	return [[self URLEncodedString] dataUsingEncoding:NSUTF8StringEncoding];
}

+ (id)dictionaryWithKeysAndObjects:(id)firstKey, ... {
	va_list args;
    va_start(args, firstKey);
	NSMutableArray* keys = [NSMutableArray array];
	NSMutableArray* values = [NSMutableArray array];
    for (id key = firstKey; key != nil; key = va_arg(args, id)) {
		id value = va_arg(args, id);
        [keys addObject:key];
		[values addObject:value];		
    }
    va_end(args);
    
    return [self dictionaryWithObjects:values forKeys:keys];
} 

- (id)keyForObject:(id)object {
	for (id key in self) {
		if ([[self objectForKey:key] isEqual:object]) {
			return key;
		}
	}	
	return nil;
}

@end