Question

I am having issues with a category method used to percent-escape illegal symbols.

This is the code that i am using for the task:

@implementation NSString (URLEncoding)
-(NSString *)urlEncodeUsingEncoding:(NSStringEncoding)encoding {
    NSString *s = (NSString *)CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)self, NULL, (CFStringRef)@"!*'\"();:@&=+$,/?%#[]% ",CFStringConvertNSStringEncodingToEncoding(encoding));
    NSLog(@"S: %@, Self: %@", s, self);
    return [s autorelease];
}
@end

When ever i run this method on a string without any of the symbols found in the above matching-string, the method runs fine and the same string is returned back to me.

For instance if i have a string like @"test" it will output:

S: test, Self: test

But if i instead use a string like @"test&symbols" it will output:

S: null, Self: test&symbols

Hence something seems to be wrong with the use of CFURLCreateStringByAddingPercentEscapes.

Now i want to escape symbols such as & because they can occur in strings used as values in a query string, which would cause the query string to be misinterpreted.

Any idea’s about what may be the issue here?

Thank you in advance! / Magnus

Answer 1

After finding out my big mistake.
I was told to answer the question to my self.

What i did wrong that i didn’t pass NSStringEncoding value to the method, like NSUTF8StringEncoding but instead of that I was passing a CF value such as kCFStringEncodingUTF8.

The value is passed thru a converter to make it CF value which caused an error and it was already had the correct type.

Sorry for any inconvenience.

-Magnus