AFNetworking : How to know if response is using ca

问题:

I can't find any answer to my question, may be I miss something...

When I ask for a url, I need to know if the response comes from the cache or from the net.

Is the status code 304 or 200 ? (but AFNetworking always responde 200)

With ASIHTTPRequest I used to check "didUseCachedResponse" from ASIHTTPRequest, this was perfect.

回答1:

I think I found a solution to determine if response was returned from cache or not using AFNetworking 2.0. I found out that each time a new response is returned from the server (status 200, not 304) the cacheResponseBlock which is a property of AFHTTPRequestOperation is called. The block should return NSCachedURLResponse if response should be cached or nil if it shouldn't. That's way you can filter responses and cache only some of them. In this case, I am caching all responses that comes from the server. The trick is, that when server sends 304 and response is loaded from cache, this block won't be called. So, this is the code I am using:

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];

BOOL __block responseFromCache = YES; // yes by default

void (^requestSuccessBlock)(AFHTTPRequestOperation *operation, id responseObject) = ^(AFHTTPRequestOperation *operation, id responseObject) {
    if (responseFromCache) {
        // response was returned from cache
        NSLog(@"RESPONSE FROM CACHE: %@", responseObject);
    }
    else {
        // response was returned from the server, not from cache
        NSLog(@"RESPONSE: %@", responseObject);
    }
};

void (^requestFailureBlock)(AFHTTPRequestOperation *operation, NSError *error) = ^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"ERROR: %@", error);
};

AFHTTPRequestOperation *operation = [manager GET:@"http://example.com/"
                                      parameters:nil
                                         success:requestSuccessBlock
                                         failure:requestFailureBlock];

[operation setCacheResponseBlock:^NSCachedURLResponse *(NSURLConnection *connection, NSCachedURLResponse *cachedResponse) {
    // this will be called whenever server returns status code 200, not 304
    responseFromCache = NO;
    return cachedResponse;
}];

This solution works for me and I haven't found any issues so far. But, if you have a better idea or some objections against my solution, feel free to comment!

回答2:

seems that apple doesn't want you to know if it comes from cache or not.

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...

回答3:

There is a way to specify the status codes that should be treated as success in AFNetworking, it is done through response serialization, here is the code

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

AFHTTPResponseSerializer *respSerializer = [AFHTTPResponseSerializer serializer];
NSMutableIndexSet *responseCodes = [NSMutableIndexSet indexSet];
[responseCodes addIndex:200];
[responseCodes addIndex:304];

[operation setResponseSerializer:respSerializer];

With this code AFNetworking will treat 304 as success