Setting NSURLRequestCachePolicy and NSURLSession

Question

I'm creating an NSURLSession with a sessionConfiguration where I have explicitly set the requestCachePolicy and URLCache.

sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
sessionConfiguration.requestCachePolicy = NSURLRequestReturnCacheDataElseLoad;
sessionConfiguration.URLCache = [NSURLCache sharedURLCache];

A request is created and passed as an argument in NSURLSession dataTaskWithRequest:CompletionHandler: method. The request is constructed like this:

request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReturnCacheDataElseLoad timeoutInterval:kAENServiceNetworkTimeout];

Problem 1:

Setting up like this, no fsCachedData Folder is created on disk and cached data is not used. If the request is created simply using:

request = [NSMutableURLRequest requestWithURL:url];

The cache is created on disk, and the image is used as expected. Is this a bug in Apple's code?

Problem 2:

In neither of these cases is the URLSession:dataTask:willCacheResponse:completionHandler: delegate method called. Are their situations under which this would be the case?

Update:

I've pushed an example project to Github, https://github.com/mattmorton/cache-testing

Answer 1

Problem 1:

I think my understanding of the NSURLRequestReturnCacheDataElseLoad was incorrect. In this case the response is not cached.

Problem 2:

From Apple header for NSURLSession in the NSURLSessionAsynchronousConvenience category:

data task convenience methods...create tasks that bypass the normal delegate calls for response and data delivery, and provide a simple cancelable asynchronous interface to receiving data.

I am using a convenience method handler, hence why the delegate method is not being called.