AFNetworking and response cache handling

Question

In my project I'm using AFNetworking for downloading data from the web. I'm leveraging NSURLRequestUseProtocolCachePolicy on my NSURLRequest to serve user cached data (if cache is valid). This is my code:

Request method:

// create NSURL request
NSURLRequest *request = [ServerFactory URLGETRequestWithURL:url];

//creating AFHTTPRequestOperation
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

//set serializaer
operation.responseSerializer = [AFJSONResponseSerializer serializer];

//need to specify that text is acceptable content type, otherwise the error occurs
operation.responseSerializer.acceptableContentTypes = [MyRepository acceptableContentTypes];

//running fetch request async
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {  
    //parse data
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    //error handling
}];

//start async operation
[operation start];

Acceptable content types method

+ (NSSet *)acceptableContentTypes
{
    return [NSSet setWithObjects:@"application/json", @"text/plain", @"text/html" ,nil];
}

ServerFactory get methods

+ (NSURLRequest *)URLGETRequestWithURL:(NSString *)URL
{
    NSMutableURLRequest *request = [[ServerFactory URLRequestWithURL:URL] mutableCopy];
    [request setCachePolicy:NSURLRequestUseProtocolCachePolicy];
    [request setHTTPMethod:@"GET"];
    return request;
}

+ (NSURLRequest *)URLRequestWithURL:(NSString *)URL 
{
    // creating NSURL to give to NSURLRequest
    NSURL *theURL = [NSURL URLWithString:URL];

    //adding service version in http header
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:theURL];
    [request addValue:HTTP_HEADER_VERSION_VALUE forHTTPHeaderField:HTTP_HEADER_VERSION_NAME];

    //returing request
    return request;
}

Now I would like to transition to new logic:

• Get cached data
• If cached data valid
  • Serve user with cached data
  • Dispatch new request with If-Modified-Since header set to retrieved cached data time stamp
  • Server respondes 304 Not Modified if cache is still OK, or 200 OK if there is new data
  • Update UI with new data
• If cache data expired
  • Get new data from web

So basically I would like to serve cached data but check if my cached data is still valid on the server or if there's new data to download. Is there a way to achieve this? I tried with setCacheResponseBlock on AFHTTPRequestOperation but I can't get cached data timestamp. Is there a "smarter" way to do this?

Answer 1

Check out AFNetworking : How to know if response is using cache or not ? 304 or 200

"I found a way by saving modification-date associate with the request, and I compare this date when AFNetWorking answers to me.

not as clean as I intend, but works..."