Url Special Characters encoding

NSString *str=@"!*'();:@&=+$,/?%#[]";//put the url here...

NSString *encodedStr=(NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(
                                                                          NULL,
                                                                          (CFStringRef)str,
                                                                          NULL,
                                                                          CFSTR("!*'();:@&=+$,/?%#[]"),
                                                                          kCFStringEncodingUTF8));
NSLog(@"after encoding = %@",encodedStr);