NSURL with Curly Braces

Question

NSURL does not support the use of curly braces (i.e. {}) in URLs. My application needs to talk to a server that requires the use of curly braces in the URL. I'm considering using bridges to write the networking code in Python or C++, or even rewriting the C code for NSURL to make it accept curly braces. Percent escapes are not accepted by my remote server.

Do I have any other good alternatives?

EDIT: Explained why addingPercentEscapesUsingEncoding and the like don't work for me here.

Answer 1

Will it work for you if you escape the braces?

This code:

// escape {} with %7B and %7D
NSURL *url = [NSURL URLWithString:@"http://somesite.com/%7B7B643FB915-845C-4A76-A071-677D62157FE07D%7D.htm"];
NSLog(@"%@", url);

// {} don't work and return null
NSURL *badurl = [NSURL URLWithString:@"http://somesite.com/{7B643FB915-845C-4A76-A071-677D62157FE07D}.htm"];
NSLog(@"%@", badurl);

Outputs:

2011-11-30 21:25:06.655 Craplet[48922:707] http://somesite.com/%7B7B643FB915-845C-4A76-A071-677D62157FE07D%7D.htm
2011-11-30 21:25:06.665 Craplet[48922:707] (null)

So, escaping seems to work

Here's how you can programmatically escape the url:

NSString *escapedUrlString = [unescaped stringByAddingPercentEscapesUsingEncoding: NSASCIIStringEncoding];

EDIT:

In your comment below, you said your server won't accept encoded braces and was there any other alternatives. First, I would try and get the server fixed. If that's not possible ... I haven't tried this with braces etc... but the layer below NS networking classes is CFNetworking.

See this:

http://developer.apple.com/library/ios/#documentation/Networking/Conceptual/CFNetwork/CFHTTPTasks/CFHTTPTasks.html#//apple_ref/doc/uid/TP30001132-CH5-SW2

From that doc:

 CFStringRef url = CFSTR("http://www.apple.com");
 CFURLRef myURL = CFURLCreateWithString(kCFAllocatorDefault, url, NULL);
 CFStringRef requestMethod = CFSTR("GET");

 ....

Once again, haven't tried it and I'm running out. might try it later but if a layer isn't working your first options are to move down the stack.

Answer 2

Bryan's answer is perfectly great (+1 to him!), but another solution would be to use NSString's stringByAddingPercentEscapesUsingEncoding: method.

Like this:

NSString * originalURLAsString = [NSString stringWithString: @"http://somesite.com/{7B643FB915-845C-4A76-A071-677D62157FE07D}.htm"];
NSString * properlyEncodedString = [originalURLAsString stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding];
NSURL * url = [NSURL URLWithString: properlyEncodedString];

I hope this info helps you out!

Answer 3

To call using CFNetwork can use the follwoing

-(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

But even the above method 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 other suggestions to resolve this posts issue?