object from json keypath

ObjectForKeypath.m

/*
* usage:
* [self objectForKeypath:@"someKey.3.someNestedKey.2" inJSON:myJSONObject];
*/
- (id)objectForKeypath:(NSString *)keypath inJSON:(NSData *)json {
	if (!keypath || !json) {return nil;}
	
	__block NSInteger depth = 0;
	NSArray *keys = [keypath componentsSeparatedByString:@"."];
	id result = [NSJSONSerialization JSONObjectWithData:json options:kNilOptions error:nil];
	
	id (^objectAtPath)(NSString *, id) = ^id(NSString *path, id collection) {
		if (collection) {
			
			depth++;
			if ([collection isKindOfClass:[NSDictionary class]]) {
				return [(NSDictionary *)collection objectForKey:path];
			}

			else if ([collection isKindOfClass:[NSArray class]]) {
				return [(NSArray *)collection objectAtIndex:[path integerValue]];
			}
		}
		
		return nil;
	};

	while (depth < keys.count) {
		
		if (!result) { return nil; }
		
		result = objectAtPath(keys[depth], result);
	}
	
	return result;
}