NSURLCache does not clear stored responses in iOS8

Question

Here is the sample function I call when i need to clear cache and make a new call to URL

- (void)clearDataFromNSURLCache:(NSString *)urlString
{
    NSURL *requestUrl = [NSURL URLWithString:urlString];
    NSURLRequest *dataUrlRequest = [NSURLRequest requestWithURL: requestUrl];

    NSURLCache * cache =[NSURLCache sharedURLCache];


    NSCachedURLResponse* cacheResponse =[cache cachedResponseForRequest:dataUrlRequest];

    if (cacheResponse) {
        NSString* dataStr = [NSString stringWithUTF8String:[[cacheResponse data] bytes]];
        NSLog(@"data str r= %@",dataStr);
        NSLog(@"url  str r= %@",[[[cacheResponse response] URL] absoluteString]);
        [cache storeCachedResponse:nil forRequest:dataUrlRequest];
        [NSURLCache setSharedURLCache:cache];
    }

    [[NSURLCache sharedURLCache] removeCachedResponseForRequest:dataUrlRequest];

    //Check if the response data has been removed/deleted from cache
    NSURLRequest *finalRequestUrlRequest = [NSURLRequest requestWithURL:requestUrl];
    NSURLCache * finalCache =[NSURLCache sharedURLCache];

    NSCachedURLResponse* finalcacheResponse =[finalCache cachedResponseForRequest:finalRequestUrlRequest];

    if (finalcacheResponse) {
        //Should not enter here
        NSString* finaldataStr = [NSString stringWithUTF8String:[[finalcacheResponse data] bytes]];
        NSLog(@"data str r= %@",finaldataStr);
        NSLog(@"url  str r= %@",[[[cacheResponse response] URL] absoluteString]);
    }
}

In iOS 6/7 the response is deleted successfully for the requestURL, but in iOS 8 it never gets deleted. I have searched but could not find any reason why this should not work in iOS8.

Any help will be appreciated…..

Antemortem

Answer 1

NSURLCache is broken on iOS 8.0.x - it never purges the cache at all, so it grows without limit. See http://blog.airsource.co.uk/2014/10/11/nsurlcache-ios8-broken/ for a detailed investigation. Cache purging is fixed in the 8.1 betas - but removeCachedResponseForRequest: is not.

removeCachedResponsesSinceDate: does appear to work on iOS 8.0 - an API that was added for 8.0, but hasn't made it to the docs yet (it is in the API diffs). I am unclear what use it is to anyone - surely what you normally want to do is remove cached responses before a particular date.

removeAllCachedResponses works as well - but that's a real sledgehammer solution.

Siloxane

I am also seeing removeCachedResponseForRequest: not working in iOS 8.3. – Demilune

Broken in 9.3 & 9.3.1 – Magbie

Still broken in 11.2 :( Unfortunately this is critical to my project's 'prefetch' capability that relies on manipulating the cache entries. Oh well... – Ineligible

on iOS11: I'm attempting to use storeCachedResponse for my question here: URLresponse is not retrieved after storing in cache using storeCachedResponse. But the API seems to not work. My guess is that both store and remove are broken. Any thoughts? – Amendatory

Still broken in iOS 12.2! – Wiggle

Is it still broken on latest iOS versions? – Compressibility

@schin Don't know. Haven't needed to look. You could use the source provided on my blog article (referenced in my answer) to try it out. – Siloxane

Answer 2

I got a sufficient result reseting the cached response for a specific URL, changing the cache control to something that would never be returned like a "max-age=0" in the header. Look here

Infante

Answer 3

Whenever any API call is generated, That response is saved in the cache. You are able to find that folder in your documents directory, a folder with named cachedb is created which contains a list of responses. It can be a major concern related to security. With any third-party tool, someone can have access to that information.

Below is the way I have solved this issue :

NSURLCache *cache = [[NSURLCache alloc] initWithMemoryCapacity:0 * 1024 * 1024 diskCapacity:0 * 1024 * 1024 diskPath:nil]; [NSURLCache setSharedURLCache:cache];

I have allocated 0 memory space to the cache. so no data will be stored in Cache memory.

Backbend

This was old issue in iOS8.... Maybe newer version this issue is not present... Thanks for response... – Antemortem