Is it possible to prevent an NSURLRequest from caching data or remove cached data following a request?

8 thoughts on “Is it possible to prevent an NSURLRequest from caching data or remove cached data following a request?”

1. user November 30, -0001 at 12:00 am

   Would it be possible it's not cache related? Have you tried inspecting the data to see if data that should have been reloaded is in fact the old one? Maybe your leek is coming from elsewhere. How do you initialize and free the NSURLRequests? That might be of help to diagnose the problem.

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2. user November 30, -0001 at 12:00 am

   FYI – If you want to remove the files by brute force, there is example code to do that here: salesforce.stackexchange.com/a/69736

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3. user November 30, -0001 at 12:00 am

   If you use NSURLConnection take a look at the delegate:

   - (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse
   

   Return Value

   The actual cached response to store in the cache. The delegate may return cachedResponse unmodified, return a modified cached response, or return nil if no cached response should be stored for the connection.

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4. user November 30, -0001 at 12:00 am

   Usually it’s easier to create the request like this

   NSURLRequest *request = [NSURLRequest requestWithURL:url
         cachePolicy:NSURLRequestReloadIgnoringCacheData
         timeoutInterval:60.0];
   

   Then create the connection

   NSURLConnection *conn = [NSURLConnection connectionWithRequest:request
          delegate:self];
   

   and implement the connection:willCacheResponse: method on the delegate. Just returning nil should do it.

   - (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
     return nil;
   }
   

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5. user November 30, -0001 at 12:00 am

   I have the same problem in my app when I requested info from twitter. In my case I didn’t need to preserve those credentials, so I simple erase them using the next code:

   - (void) eraseCredentials{
   NSURLCredentialStorage *credentialsStorage = [NSURLCredentialStorage sharedCredentialStorage];
   NSDictionary *allCredentials = [credentialsStorage allCredentials];
   
   //iterate through all credentials to find the twitter host
   for (NSURLProtectionSpace *protectionSpace in allCredentials)
       if ([[protectionSpace host] isEqualToString:@"twitter.com"]){
           //to get the twitter's credentials
           NSDictionary *credentials = [credentialsStorage credentialsForProtectionSpace:protectionSpace];
           //iterate through twitter's credentials, and erase them all
           for (NSString *credentialKey in credentials)
               [credentialsStorage removeCredential:[credentials objectForKey:credentialKey] forProtectionSpace:protectionSpace];
       }
   }
   

   I hope it works for somebody 🙂

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6. user November 30, -0001 at 12:00 am

   If not specific to a single request(U want disable cache for whole app) below one is the best option.Add this code in app delegate or based on ur need any where

           int cacheSizeMemory = 0; // 0MB
           int cacheSizeDisk = 0; // 0MB
           NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:cacheSizeMemory diskCapacity:cacheSizeDisk diskPath:@"nsurlcache"];
           [NSURLCache setSharedURLCache:sharedCache];
   

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7. user November 30, -0001 at 12:00 am

   If you’re using NSURLSession, another solution to prevent request and parameters being written to the Cache.db iOS creates within the app’s Caches directory, is to set the NSURLCache for the session’s configuration to a 0 size memory and 0 size disk cache e.g.

   let configuration = URLSessionConfiguration.default    
   configuration.urlCache = URLCache(memoryCapacity: 0, diskCapacity: 0, diskPath: nil)
   let session = URLSession(configuration: configuration)
   

   or as mentioned above set at a global cache level

   URLCache.shared = URLCache(memoryCapacity: 0, diskCapacity: 0, diskPath: nil)
   

   Presumably it’s the 0 for disk size that stops iOS writing to disk but if you have a policy to reloadIgnoringLocalCacheData then you probably aren’t interested in memory caching either.

   Note This will prevent any Caches/Cache.db (requests & responses) or Caches/fsCachedData/ folder (response data) being created at all. We’ve decided to take this approach in an app for security purposes as we don’t want our requests to be stored on disk cache ever.

   If anyone knows is there’s a way to stop only request caching but keep response data caching from the iOS URL Loading mechanism, I’d be interested to know. (there’s no API or official documentation about this from what I can tell)

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8. user November 30, -0001 at 12:00 am

   NSMutableURLRequest* request = [[NSMutableURLRequest alloc] url];
   [request setValue:@"no-store" forHTTPHeaderField:@"Cache-Control"];
   [request setCachePolicy:NSURLRequestReloadIgnoringLocalCacheData];
   

   Assuming the server is correctly implemented, putting the Cache-Control:no-store header in the request will generate a server response with the same header, thus causing NSURLCache to not store the response data on disk.

   Therefore, no need for the shotgun approach of disabling NSURLCache disk caching.

   PS: Adding the header should work for all HTTP frameworks, like AFNetworking

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