NSCachedURLResponse returns object, but UIWebView does not interprets content

Question

I am sending a request to a UIWebView. There are AJAX-calls on the loaded webpage. I need to analyze the AJAX-traffic in order to determinate, if the user is logged in or not. For doing this I installed a NSURLCache in the AppDelegate:

MYURLCache *cache = [[MYURLCache alloc] init];
[NSURLCache setSharedURLCache:cache];

This MYURLCache-class correctly receives the traffic that runs through the webview. I can terminate the AJAX-calls only. I then spawn an own request of the AJAX-calls. This one returns the perfectly fine response from the webserver. So the last step to do now is constructing the NSCachedURLResponse return object. I also managed this, but the webview simply does nothing when returning the objects. If I return just nil, the WebView loads everything fine (nil is the message for the NSURLCache, that nothing is cached, so the webview should start to load it on its own).

- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request {
    if ([[[request URL] absoluteString] rangeOfString:@"/ajax/"].location == NSNotFound) {
        return nil;
    } else {

    ASIHTTPRequest *asirequest = [ASIHTTPRequest requestWithURL:[request URL]];
    [asirequest setValidatesSecureCertificate:NO];
    [asirequest startSynchronous];
    NSError *error = [asirequest error];
    NSData* data = [[asirequest responseString] dataUsingEncoding:NSUTF8StringEncoding];

    // Create the cacheable response
    NSURLResponse *urlresponse = [[NSURLResponse alloc] initWithURL:[request URL] MIMEType:@"application/json" expectedContentLength:[data length] textEncodingName:@"UTF-8"];
    NSCachedURLResponse *cachedResponse = [[NSCachedURLResponse alloc] initWithResponse:urlresponse data:data];

    NSLog(@"cachedResponse %@", cachedResponse);
    NSLog(@"cachedResponse data %@", [[NSString alloc] initWithData:[cachedResponse data] encoding:NSUTF8StringEncoding]);

    return cachedResponse;
}  

return nil;
}

Answer 1

I found one solution to this problem... I think it has got something to do with the headers that were missing.

If I replace

NSURLResponse *urlresponse = [[NSURLResponse alloc] initWithURL:[request URL] MIMEType:@"application/json" expectedContentLength:[data length] textEncodingName:@"UTF-8"];
NSCachedURLResponse *cachedResponse = [[NSCachedURLResponse alloc] initWithResponse:urlresponse data:data];

With

NSHTTPURLResponse *urlresponse = [[NSHTTPURLResponse alloc] initWithURL:request.URL statusCode:200 HTTPVersion:@"1.1" headerFields:nil];
NSCachedURLResponse *cachedResponse = [[NSCachedURLResponse alloc] initWithResponse:urlresponse data:data];

The whole thing works. This answer in addition suggested the additional custom header of the request. https://stackoverflow.com/a/15234850/274518

NSDictionary *headers = @{@"Access-Control-Allow-Origin" : @"*", @"Access-Control-Allow-Headers" : @"Content-Type"};
NSHTTPURLResponse *urlresponse = [[NSHTTPURLResponse alloc] initWithURL:request.URL statusCode:200 HTTPVersion:@"1.1" headerFields:headers];

In my case I did not needed it.