Objective-c iPhone percent encode a string?

Question

I would like to get the percent encoded string for these specific letters, how to do that in objective-c?

Reserved characters after percent-encoding !   *   '   (   )   ;   :   @   &   =   +   $   ,   /   ?   #   [   ] %21 %2A %27 %28 %29 %3B %3A %40 %26 %3D %2B %24 %2C %2F %3F %23 %5B %5D 

Percent-encoding wiki

Please test with this string and see if it do work:

myURL = @"someurl/somecontent" 

I would like the string to look like:

myEncodedURL = @"someurl%2Fsomecontent" 

I tried with the stringByAddingPercentEscapesUsingEncoding: NSASCIIStringEncoding already but it does not work, the result is still the same as the original string. Please advice.

Answer 1

I've found that both stringByAddingPercentEscapesUsingEncoding: and CFURLCreateStringByAddingPercentEscapes() are inadequate. The NSString method misses quite a few characters, and the CF function only lets you say which (specific) characters you want to escape. The proper specification is to escape all characters except a small set.

To fix this, I created an NSString category method to properly encode a string. It will percent encoding everything EXCEPT [a-zA-Z0-9.-_~] and will also encode spaces as + (according to this specification). It will also properly handle encoding unicode characters.

- (NSString *) URLEncodedString_ch {     NSMutableString * output = [NSMutableString string];     const unsigned char * source = (const unsigned char *)[self UTF8String];     int sourceLen = strlen((const char *)source);     for (int i = 0; i < sourceLen; ++i) {         const unsigned char thisChar = source[i];         if (thisChar == ' '){             [output appendString:@"+"];         } else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' ||                     (thisChar >= 'a' && thisChar <= 'z') ||                    (thisChar >= 'A' && thisChar <= 'Z') ||                    (thisChar >= '0' && thisChar <= '9')) {             [output appendFormat:@"%c", thisChar];         } else {             [output appendFormat:@"%%%02X", thisChar];         }     }     return output; }