Escape Quotes in Objective-C

Question

I'm using this code snippet to encode characters to be friendly with a POST request:

   NSString *unescaped = [textField text];
   NSString *escapedString = (__bridge_transfer NSString *)CFURLCreateStringByAddingPercentEscapes(
                                                                                  NULL,
                                                                                  (__bridge_retained CFStringRef)unescaped,
                                                                                  NULL,
                                                                                  (CFStringRef)@"!*'();:@&=+$,/?%#[]",
                                                                                  kCFStringEncodingUTF8);

Which works great, but does not add escape Quotation marks: "

How do I escape Quotation marks in IOS?

Answer 1

I needed to take the user inputted NSString from [textField text] and make sure that if there are quotation marks in the string, they are escaped properly in order to send through a POST statement.

My solution was:

unescaped = [unescaped stringByReplacingOccurrencesOfString:@"\"" withString:@"\\\""];

Answer 2

First, you don't want to use __bridge_retained in your cast to a CFStringRef. Just use __bridge.

Second, you don't have to escape the quotes manually by string replacement. Just add the quote character to the set of characters to be quoted when calling CFURLCreateStringByAddingPercentEscapes(). Like so:

NSString *unescaped = [textField text];
NSString *escapedString = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(NULL,
                                                                                    (__bridge CFStringRef)unescaped,
                                                                                    NULL,
                                                                                    CFSTR("!*'();:@&=+$,/?%#[]\""),
                                                                                    kCFStringEncodingUTF8));

(In addition to adding the quote to the set, I changed to use CFBridgingRelease() rather than a __bridge_transfer cast because I find it clearer. It satisfies the feeling that all CF "Create" functions need a corresponding "Release". Also, I changed the use of a @"" literal cast to CFStringRef to just a CFSTR("") literal.)

Answer 3

Quotes are to be escaped with \".

As in:

(CFStringRef)@"I'm an \"example\""