While writing a parser for generic queries I’ve discovered a very useful method of NSString named stringByReplacingPercentEscapesUsingEncoding. Yeah, I can agree that such method name fully describes what it does, but geez, the source is so hard to read!
[d setValue:
[[s substringFromIndex:r.location+1] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]
forKey:
[[s substringToIndex:r.location] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]
];