NSDictionaryをクエリ文字列にする
-(NSString*)getQueryStringByDic:(NSDictionary*)dic
{
    NSArray*keys = [dic allKeys];
    NSMutableArray*tmp=[NSMutableArray array];
    for (NSString*key in keys) {
        [tmp addObject:[NSString stringWithFormat:@"%@=%@",key,dic[key]]];
    }
    return [tmp componentsJoinedByString:@"&"];
}
-(NSString*)getEncodedQueryStringByDic:(NSDictionary*)dic
{
    NSArray*keys = [dic allKeys];
    NSMutableArray*tmp=[NSMutableArray array];
    for (NSString*key in keys) {
        NSString*value = dic[key];
        [tmp addObject:[NSString stringWithFormat:@"%@=%@",key,[value stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet alphanumericCharacterSet]] ]];
    }
    return [tmp componentsJoinedByString:@"&"];
}
-(IBAction)onTapButton:(id)sender
{
    NSMutableDictionary*dic=[NSMutableDictionary dictionary];
    dic[@"id"]=@"285";
    dic[@"name"]=@"jeff";
    dic[@"place"]=@"newyork";
    dic[@"version"]=@"iOS7.1";
    
    NSLog(@"%@", [self getQueryStringByDic:dic] );
}


結果
place=newyork&id=285&name=jeff&version=iOS7.1