Stretch Stretch - 6 months ago 33
iOS Question

UIWebView to view self signed websites (No private api, not NSURLConnection) - is it possible?

There's a load of questions which ask this: Can I get

UIWebView
to view a self signed HTTPS website?

And the answers always involve either:


  1. Use the private api call for
    NSURLRequest
    :
    allowsAnyHTTPSCertificateForHost

  2. Use
    NSURLConnection
    instead and the delegate
    canAuthenticateAgainstProtectionSpace
    etc



For me, these won't do.
(1) - means I can't submit to the app store successfully.
(2) - using NSURLConnection means the CSS, images and other things that have to be fetched from the server after receiving the initial HTML page do not load.

Does anyone know how to use UIWebView to view a self-signed https webpage please, which does not involve the two methods above?

Or - If using
NSURLConnection
can in fact be used to render a webpage complete with CSS, images and everything else - that would be great!

Cheers,

Stretch.

Answer

Finally I got it!

What you can do is this:

Initiate your request using UIWebView as normal. Then - in webView:shouldStartLoadWithRequest - we reply NO, and instead start an NSURLConnection with the same request.

Using NSURLConnection, you can communicate with a self-signed server, as we have the ability to control the authentication through the extra delegate methods which are not available to a UIWebView. So using connection:didReceiveAuthenticationChallenge we can authenticate against the self signed server.

Then, in connection:didReceiveData, we cancel the NSURLConnection request, and start the same request again using UIWebView - which will work now, because we've already got through the server authentication :)

Here are the relevant code snippets below.

Note: Instance variables you will see are of the following type:
UIWebView *_web
NSURLConnection *_urlConnection
NSURLRequest *_request

(I use an instance var for _request as in my case it's a POST with lots of login details, but you could change to use the request passed in as arguments to the methods if you needed.)

#pragma mark - Webview delegate

// Note: This method is particularly important. As the server is using a self signed certificate,
// we cannot use just UIWebView - as it doesn't allow for using self-certs. Instead, we stop the
// request in this method below, create an NSURLConnection (which can allow self-certs via the delegate methods
// which UIWebView does not have), authenticate using NSURLConnection, then use another UIWebView to complete
// the loading and viewing of the page. See connection:didReceiveAuthenticationChallenge to see how this works.
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType;
{
    NSLog(@"Did start loading: %@ auth:%d", [[request URL] absoluteString], _authenticated);

    if (!_authenticated) {
        _authenticated = NO;

        _urlConnection = [[NSURLConnection alloc] initWithRequest:_request delegate:self];

        [_urlConnection start];

        return NO;
    }

    return YES;
}


#pragma mark - NURLConnection delegate

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge;
{
    NSLog(@"WebController Got auth challange via NSURLConnection");

    if ([challenge previousFailureCount] == 0)
    {
        _authenticated = YES;

        NSURLCredential *credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];

        [challenge.sender useCredential:credential forAuthenticationChallenge:challenge];

    } else
    {
        [[challenge sender] cancelAuthenticationChallenge:challenge];
    }
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response;
{
    NSLog(@"WebController received response via NSURLConnection");

    // remake a webview call now that authentication has passed ok.
    _authenticated = YES;
    [_web loadRequest:_request];

    // Cancel the URL connection otherwise we double up (webview + url connection, same url = no good!)
    [_urlConnection cancel];
}

// We use this method is to accept an untrusted site which unfortunately we need to do, as our PVM servers are self signed.
- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace
{
    return [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
}

I hope this helps others with the same issue I was having!