gistfile1.m

- (CSMCacheResponse *)cachedResponseForRequestURL:(NSURL *)url
{
    __block CSMCacheResponse* cachedResponse = nil;
    __weak CSMCache* weakSelf = self;
        
    dispatch_sync(requestQueue, ^{
        
        // Keep the weak self until function returns
        __strong CSMCache* strongSelf = weakSelf;
        
        if (strongSelf.cacheDictionary &&
            url.csm_cacheKey &&
            (cachedResponse = strongSelf.cacheDictionary[url.csm_cacheKey]) &&
            [cachedResponse isKindOfClass:[CSMCacheResponse class]])
        {
            // Increment our cache hit for a URL in memory.
            [strongSelf csm_cacheHitFromMemory:url];
        }
        else
        {
            if (fileManager &&
                url.csm_cachePath &&
                [fileManager fileExistsAtPath:url.csm_cachePath.absoluteString])
            {
                @try
                {
                    cachedResponse = [NSKeyedUnarchiver unarchiveObjectWithFile:url.csm_cachePath.absoluteString];
                }
                @catch (NSException *exception)
                {
                    cachedResponse = nil;
                }
                @finally
                {
                    if (cachedResponse)
                    {
                        // Increment our cache hit for a URL on disk.
                        [strongSelf csm_cacheHitFromDisk:url];
                    }
                }
            }
        }
        
    });
    
    return cachedResponse;
}