gistfile1.m

- (void)_checkCacheOrFail:(RNCachedData *)cache
{
    if (cache)
    {
        NSHTTPURLResponse* response = (NSHTTPURLResponse *)[cache response];
        
        NSURLRequest* redirectRequest = [cache redirectRequest];
        
        if (redirectRequest)
        {
            [[self client] URLProtocol:self wasRedirectedToRequest:redirectRequest redirectResponse:response];
        }
        else
        {
            NSLog(@"Returning cached response for %@", [[self request] URL]);
            NSData *data = [[cache data] copy];
            
            NSMutableDictionary* responses = [NSMutableDictionary dictionaryWithDictionary:[response allHeaderFields]];
            [responses setValue:@"" forKey:@"csm-did-cache"];
            NSHTTPURLResponse* cachedResponse = [[NSHTTPURLResponse alloc] initWithURL:response.URL statusCode:response.statusCode HTTPVersion:@"HTTP/1.1" headerFields:responses];
        
             // we handle caching ourselves.
            [[self client] URLProtocol:self didReceiveResponse:cachedResponse cacheStoragePolicy:NSURLCacheStorageNotAllowed];
            [[self client] URLProtocol:self didLoadData:data];
            [[self client] URLProtocolDidFinishLoading:self];
        }
    }
    else
    {
        [[self client] URLProtocol:self didFailWithError:[NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorCannotConnectToHost userInfo:nil]];
    }
}