URL encoding iOS NSURL error

Question

URL which opens in Firefox,Chrome browsers on desktop, doesn't open in WebView on iPhone. This URL is supposedly accessing a GET request. When creating the NSURL without percentescaping the url doesn't get generated. When using percentescape the url redirects to a Bad url content.

Is there a different encoding used on desktop browsers and not on the iPhone? or mobile Safari? Are there different ways to encode the URL in iOS other than using

-stringByAddingPercentEscapesUsingEncoding
-CFURLCreateStringByAddingPercentEscapes

which generates bad request content pages from server.

Any help would be really great, Thanks.

EDIT:
The URL been generated is as below

http://something.test.com/iostest/index.html?{"a":"b"}

Managed to figure that not encoding the curly brackets is causing the issue in iOS. as in

NSString *tempUrlSting = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)tempURLA,CFSTR("{}"), CFSTR("\""), CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding)));
NSURL *tempUrl=[NSURL URLWithString:tempUrlSting];

1. If not encoding the braces in the URL but encoding the rest using [Rob's answer][1] as above. When creating the NSURL, the url is empty.
2. If encoding the braces the URL gets generated fine, but the server throws an exception.

This Question suggests to use CFNetworking.

EDIT
Used CFNetworking as below

-(void)getDataFromUrl{
    CFStringRef tempURLA = CFSTR("http://my.test.server/iostest/index.html?{\"a\":\"b\"}");
    CFStringRef tempUrlSting = CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)tempURLA,CFSTR("{}"), CFSTR("\""), CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));

    CFURLRef myURL = CFURLCreateWithString(kCFAllocatorDefault, tempUrlSting, NULL);

    CFStringRef requestMethod = CFSTR("GET");
    CFHTTPMessageRef myRequest = CFHTTPMessageCreateRequest(kCFAllocatorDefault, requestMethod, myURL,kCFHTTPVersion1_1);

    CFStringRef headerFieldName = CFSTR("Accept");
    CFStringRef headerFieldValue = CFSTR("text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
    CFHTTPMessageSetHeaderFieldValue(myRequest, headerFieldName, headerFieldValue);


    [self performHTTPRequest:myRequest];

}

-(void)performHTTPRequest:(CFHTTPMessageRef)request {
    CFURLRef gotdatab = (__bridge CFURLRef)(CFBridgingRelease(CFHTTPMessageCopyRequestURL(request)));
//    NSLog(@"(CFHTTPMessageRef request  %@",gotdatab);

    CFReadStreamRef requestStream = CFReadStreamCreateForHTTPRequest(NULL, request);

    CFReadStreamOpen(requestStream);

    NSMutableData *responseBytes = [NSMutableData data];
    NSError *error;

    while (TRUE) {

        if (CFReadStreamHasBytesAvailable(requestStream)) {
            UInt8 streambuffer[1024];
            int readBytes = CFReadStreamRead (requestStream,streambuffer,sizeof(streambuffer));
            NSLog(@"Read: %d",readBytes);
            [responseBytes appendBytes:streambuffer length:readBytes];
        }

        if (CFReadStreamGetStatus(requestStream) == kCFStreamStatusError) {

            error = (NSError*)CFBridgingRelease(CFReadStreamCopyError (requestStream));
            if ([error code] == 61) {
                // connection refused
                NSLog(@"Error occured: %d",[error code]);
            }
            break;
        }
        if (CFReadStreamGetStatus(requestStream) == kCFStreamStatusAtEnd) {
            NSLog(@"Stream reached end!");
            error = nil;
            break;
        }

    }//
    CFHTTPMessageRef response = (CFHTTPMessageRef)CFReadStreamCopyProperty(requestStream, kCFStreamPropertyHTTPResponseHeader);

    if (response==NULL) {
        NSLog(@"response is null");
        return;
    }
}

The above was done using examples from here and here

Above method still has the same issue. That is: if {} are not encoded the URL doesn't get generated. If the {} are encoded the server doesn't return a proper value.

Any suggestions pls?

Answer 1

You should edit your question showing us an example of your URL and your GET parameters. If you're percent escaping, for example, some reserved character in the domain name or the URL path, that suggests one solution (e.g. stringByAddingPercentEscapesUsingEncoding is fine). If you're percent escaping the broader array of reserved characters in the parameters of a GET request (notably = or +), then stringByAddingPercentEscapesUsingEncoding is simply not up to the job and you'd have to use CFURLCreateStringByAddingPercentEscapes (but only on the parameter keys and their values, not on the full URL string). I use a method like the following on the parameters as I append them to the URL:

- (NSString *)percentEscapeURLParameter:(NSString *)string
{ 
    return CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                                     (CFStringRef)string,
                                                                     NULL,
                                                                     (CFStringRef)@":/?@!$&'()*+,;=",
                                                                     kCFStringEncodingUTF8));
}

If you're saying that CFURLCreateStringByAddingPercentEscapes is not working for you, you'd have to show us how you're using it. Make sure you are doing it just on the GET parameter values, that you're supplying the necessary "legal characters to escape" parameter, that you're not escaping something that shouldn't be, etc.

Answer 2

Sometimes URL encoded format already except for the é-character which should probably be encoded as %c3%a9. Desktop browser is quite liberal with invalid URLs, thats why it works in Safari etc. So if you have a NSString and you want to convert it into a proper URL encoding then use the below method of NSString class.

NSURL* url = [NSURL URLWithString:[strURL stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];