Objective-C: url encoding

stringByURLEncodingStringParameter.m

+(NSString*)stringByURLEncodingStringParameter:(NSString*)originalStr
{
    // NSURL's stringByAddingPercentEscapesUsingEncoding: does not escape
    // some characters that should be escaped in URL parameters, like / and ?; 
    // we'll use CFURL to force the encoding of those
    //
    // We'll explicitly leave spaces unescaped now, and replace them with +'s
    //
    // Reference: [url]http://www.ietf.org/rfc/rfc3986.txt[/url]
	
    NSString *resultStr = nil;
	
    CFStringRef originalString = (__bridge CFStringRef) originalStr;
    CFStringRef leaveUnescaped = CFSTR(" ");
    CFStringRef forceEscaped = CFSTR("!*'();:@&=+$,/?%#[]");
	
    NSString *escapedStr;
    escapedStr = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                         originalString,
                                                         leaveUnescaped, 
                                                         forceEscaped,
                                                         kCFStringEncodingUTF8));
    if( escapedStr )
    {
        // replace spaces with plusses
        resultStr = [escapedStr stringByReplacingOccurrencesOfString:@" "
                                    withString:@"%20"];
    }
    return resultStr;
}

Thanks for the gist. URLs can also be encoded online using URLEncoder.io tool.