SDURLCache with AFNetworking and offline mode not working
Well I've finally reached a not so ugly workaround:
First
If you're using IOS5/IOS6 you can drop SDURLCache and use the native one:
//Set CacheNSURLCache *URLCache = [[NSURLCache alloc] initWithMemoryCapacity:4 * 1024 * 1024 diskCapacity:20 * 1024 * 1024 diskPath:nil];[NSURLCache setSharedURLCache:URLCache];
But remember that in IOS5 https requests wont be cached in IOS6 they will.
Second
We need to add the following frameworks to our Prefix.pch
so AFNetworking can start monitoring our internet connection.
#import <MobileCoreServices/MobileCoreServices.h>#import <SystemConfiguration/SystemConfiguration.h>
Third
We need and AFHTTPClient instance so we can intercept every outgoing request and change his cachePolicy
-(NSMutableURLRequest *)requestWithMethod:(NSString *)method path:(NSString *)path parameters:(NSDictionary *)parameters { NSMutableURLRequest * request = [super requestWithMethod:method path:path parameters:parameters]; if (request.cachePolicy == NSURLRequestUseProtocolCachePolicy && self.networkReachabilityStatus == AFNetworkReachabilityStatusNotReachable) { request.cachePolicy = NSURLRequestReturnCacheDataDontLoad; } if (self.networkReachabilityStatus == AFNetworkReachabilityStatusUnknown) { puts("uknown reachability status"); } return request;}
With these peaces of code we can now detect when the wifi/3g is unavailable and the specify the request to use always the cache no matter what. (Offline Mode)
Notes
I still don't know what to do when the
networkReachabilityStatus
isAFNetworkReachabilityStatusUnknown
This can happen is a request is made as soon as the application starts and AF has not obtained the internet status yet.Remember that in order for this to work the server has to set the correct cache headers in the http response.
UPDATE
Looks like IOS6 has some problems loading cached responses in no-internet situations, so even if the request is cached and the request cache policy is seted to NSURLRequestReturnCacheDataDontLoad
the request will fail.
So an ugly workaround is to modify (void)connection:(NSURLConnection __unused *)connection didFailWithError:(NSError *)error
in AFURLConnectionOperation.m
to retrieve the cached response if the request fails but only for specific cache policies.
- (void)connection:(NSURLConnection __unused *)connection didFailWithError:(NSError *)error{ self.error = error; [self.outputStream close]; [self finish]; self.connection = nil; //Ugly hack for making the request succeed if we can find a valid non-empty cached request //This is because IOS6 is not handling cache responses right when we are in a no-connection sittuation //Only use this code for cache policies that are supposed to listen to cache regarding it's expiration date if (self.request.cachePolicy == NSURLRequestUseProtocolCachePolicy || self.request.cachePolicy == NSURLRequestReturnCacheDataElseLoad || self.request.cachePolicy == NSURLRequestReturnCacheDataDontLoad) { NSCachedURLResponse * cachedResponse = [[NSURLCache sharedURLCache] cachedResponseForRequest:self.request]; if (cachedResponse.data.length > 0) { self.responseData = cachedResponse.data; self.response = cachedResponse.response; self.error = nil; } }}
Can't tell much without your HTTP headers -- but the most common reason for this is NSURLProtocol
forcing revalidation before delivering cached response to WebView.
Please take a look here :http://robnapier.net/blog/offline-uiwebview-nsurlprotocol-588
It sounds like you want the request to succeed, even though the cache says the data has expired and should be retrieved from the server. You may have some luck setting the cache policy (different policy for online vs. offline) of certain requests where you'd rather use stale data than fail.
NSMutableURLRequest -> setCachePolicy
It looks like NSURLRequestReturnCacheDataDontLoad
is the policy you want for offline mode.
Hope that helps!