NSString method to percent escape '&' for URL

Question

Which NSString encoding method will percent escape the ampersand (&) character correctly into %26?

stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding

gets the spaces (%20) and other baddies but ignores ampersands!?!

Answer 1

Ampersands won't be processed by that method because they're legal characters in a URL. You should probably pre-process particularly problematic pieces, piecemeal, prior to this call.