NSURLCache not caching

Question

So I have subclassed NSURLCache and every time I call loadHTMLFromString: it calls storeCachedRequest:forRequest: and then cachedResponseForRequest:. Here's what I have:

- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request
{
    NSString *pathString = [[request URL] absoluteString];

    NSCachedURLResponse * response = [super cachedResponseForRequest:request];
    if (response != nil)
        return response;
    else {
        NSString* myString= @"testing";

        NSData* data=[myString dataUsingEncoding: NSASCIIStringEncoding ];

        //
        // Create the cacheable response
        //
        NSURLResponse *response =
        [[[NSURLResponse alloc]
          initWithURL:[request URL]
          MIMEType:[self mimeTypeForPath:pathString]
          expectedContentLength:[data length]
          textEncodingName:nil]
         autorelease];
        NSCachedURLResponse * cachedResponse =
        [[[NSCachedURLResponse alloc] initWithResponse:response data:data] autorelease];

        [self storeCachedResponse:cachedResponse forRequest:request] ;

        //NSLog(@"DEFAULT CACHE WITH URL %@", [[request URL] absoluteString]);
        return [super cachedResponseForRequest:request];
    }

    return nil;
}

- (void)storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(NSURLRequest *)request
{
    [super storeCachedResponse:cachedResponse forRequest:request];

    NSLog(@"STORE CACHED RESPONSE WITH URL %@", [[request URL] absoluteString]);
}

The issue is that when I call cachedResponseForRequest: right after it is saved, the response is always nil. Why is this?

I had:

NSURLRequest * req = [NSURLRequest requestWithURL:[NSURL URLWithString:self.imageSource_]];
NSCachedURLResponse * response = [[NSURLCache sharedURLCache] cachedResponseForRequest:req];

if (response == nil)
    NSLog(@"RESPONSE IS NIL");
else {
    NSString* theString = [[NSString alloc] initWithData:response.data encoding:NSASCIIStringEncoding];
    NSLog(@"RESPONSE IS NOT NIL %@", theString);
}

and it always prints response is nil. The url string is the same as it was when it storeCachedResponse. For some reason it is not caching. I've set the cache size to some amount of size.

score 1 · Answer 1 · answered Nov 26 '12 at 07:21

1

The default NSURLCache seems to be pretty random when choosing what to cache or not. Your best bet may be to subclass it and handle caching of the files you mind directly in cachedResponseForRequest: and leaving the rest for super.

answered Nov 26 '12 at 07:21

Rivera

10,792
3
58
102

score 1 · Answer 2 · answered Jan 20 '12 at 03:56

1

Not 100% sure, but I think you need to use the NSURLResponse that got returned by your NSURLConnection instead of creating your own. My suspicion is that if you just create a NSURLResponse it doesn't have any headers set for the caching, and so NSURLCache assumes it should cache this particular result.

answered Jan 20 '12 at 03:56

Johan Kool

15,637
8
64
81

hmmm... are you sure about that? because storeCachedResponse was called right before cachedResponseForRequest and response == nil in that method – adit Jan 20 '12 at 03:59
so even if I am not creating my own NSURLResponse, it still doesn't saves it – adit Jan 20 '12 at 03:59
"hmmm... are you sure about that?" Read the first three words of my answer again. ;-) – Johan Kool Jan 20 '12 at 04:47
Does your server send out the proper cache headers? – Johan Kool Jan 20 '12 at 04:48
yes it does, anyway I decided to just use SDURLCache and it works much better – adit Jan 20 '12 at 05:06

NSURLCache not caching

2 Answers2