Make an NSURL with an encoded plus (+)

Question

I need to pass a timestamp with a timezone offset in a GET request, e.g.,

2009-05-04T11:22:00+01:00

This looks like a two arguments "2009-05-04T11:22:00" and "01:00" to the receiving PHP script (over which I've no control).

NSURL doesn't encode plus signs, but if I make an NSURL using the string

2009-05-04T11:22:00%2B01:00

the url I end up with contains:

2009-05-04T11:22:00%252B01:00

Any ideas how I can preserve my encoded plus sign or just plain prevent NSURL from encoding anything?

Answer 1

Thought I may as well provide my workaround as an answer, as I don't think there's a good solution to the original problem.

The plus sign (+) is completely valid in a URL, so my solution was to convert the time to GMT and remove the timezone/DST offset from the string. I'll leave it as an exercise for the reader to determine the value of secondsFromGMT below as, in my case, it's always the same because I'm only interested in timestamps generated by a web server.

NSString *gmtWhen = [[self descriptionWithCalendarFormat:nil
                           timeZone:[NSTimeZone
                           timeZoneForSecondsFromGMT:secondsFromGMT
                     ] locale:nil] stringByReplacingOccurrencesOfString:@" +0000" withString:@""];

Answer 2

Use NSString's stringByAddingPercentEscapesUsingEncoding: method on the text you want to include as an argument.

As its name implies, the method will convert return an auto-released string containing an url-safe version of the receiver.

Answer 3

To get encoded plus (%2B) (It works with all charcters) use CFURLCreateStringByAddingPercentEscapes as

/**
 get parameterized url from url and query parameters.
 */
+(NSString *)getParameterizedUrl:(NSString *)url withParameters:(NSDictionary *)queryDictionary
{
    NSMutableArray *mutablePairs = [NSMutableArray array];
    for (NSString *key in queryDictionary) {
        [mutablePairs addObject:[NSString stringWithFormat:@"%@=%@", CTPercentEscapedQueryStringKeyFromStringWithEncoding(key, NSUTF8StringEncoding), CTPercentEscapedQueryStringValueFromStringWithEncoding(queryDictionary[key], NSUTF8StringEncoding)]];
    }

    return [[NSString alloc]initWithFormat:@"%@?%@",url,[mutablePairs componentsJoinedByString:@"&"]];
}

static NSString * const kCharactersToBeEscapedInQueryString = @":/?&=;+!@#$()',*";

static NSString * CTPercentEscapedQueryStringKeyFromStringWithEncoding(NSString *string, NSStringEncoding encoding) {
    static NSString * const kCharactersToLeaveUnescapedInQueryStringPairKey = @"[].";

    return (__bridge_transfer  NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (__bridge CFStringRef)string, (__bridge CFStringRef)kCharactersToLeaveUnescapedInQueryStringPairKey, (__bridge CFStringRef)kCharactersToBeEscapedInQueryString, CFStringConvertNSStringEncodingToEncoding(encoding));
}

static NSString * CTPercentEscapedQueryStringValueFromStringWithEncoding(NSString *string, NSStringEncoding encoding) {
    return (__bridge_transfer  NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (__bridge CFStringRef)string, NULL, (__bridge CFStringRef)kCharactersToBeEscapedInQueryString, CFStringConvertNSStringEncodingToEncoding(encoding));
}

And use in your code as

NSMutableDictionary *params = [[NSMutableDictionary alloc]init];
[params setObject:@"2009-05-04T11:22:00+01:00" forKey:@"timestamp"];

NSString *urlString = [self getParameterizedUrl:@"http://www.example.com" withParameters:params];
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

Answer 4

encode you string by using below code

NSString *result = (NSString *)CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)self,NULL,(CFStringRef)@"+",kCFStringEncodingUTF8);

this will encode + of you string which will prevent replacement of + by %2b while posting data in post method

Answer 5

Solution when using URLComponents (Swift 3):

var params = ["email": "[e-mail]", "name": "John Brown"]
var components = URLComponents(string: "http://www.example.com")!
components.path = "/login"
components.queryItems = params.map { URLQueryItem(name: $0, value: $1) }

let url_NoFix = components.url!
// http://www.example.com/login?name=John%20Brown&email=[e-mail]

let cs = CharacterSet(charactersIn: "+").inverted
let q =  components.percentEncodedQuery?.addingPercentEncoding(withAllowedCharacters: cs)
components.percentEncodedQuery = q

let url_Fixed = components.url!
// http://www.example.com/login?name=John%20Brown&email=[e-mail]

Answer 6

What worked for me was doing the UTF8 conversion, then replacing the + sign with %2B:

NSString *urlString =
    [NSString stringWithFormat:@"%@/iphone/push/create?pn[token]=%@&pn[send_at]=%@",
     kHTTPURL, appDelegate.deviceAPNToken, [dateTimeToUse description]];

urlString =
    [[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]
     stringByReplacingOccurrencesOfString:@"+" withString:@"%2B"];