grantland/README.md

## README.md

      
    Raw
  

              README.md
            
          
    NSURLCache uses more than just the HTTP method and URL properties of NSURLRequest as the key for its cache. Therefore, it is possible for a request with method=GET and URL=X to return a miss with NSURLCache even though a NSCachedURLResponse was stored with method=GET and URL=X. These misses can be caused by non-http properties of NSURLRequest being different than the NSURLRequest used to store the NSCachedURLResponse.
We've seen the following show up as a miss:
NSURLCache * cache = //...    
NSURL *url = [NSURL URLWithString:@"http://example.com"];
NSURLRequestCachePolicy cachePolicy = NSURLRequestReturnCacheDataElseLoad;
NSURLRequest r1 = [NSURLRequest requestWithURL:url cachePolicy:cachePolicy timeoutInterval:30];
NSURLRequest r2 = [NSURLRequest requestWithURL:url cachePolicy:cachePolicy timeoutInterval:60];

[cache storeCachedResponse:/*response*/ forRequest:r1];
[cache cachedResponseForRequest:r1]; // HIT
[cache cachedResponseForRequest:r2]; // MISS

In order to get around this, you could write a key generator that canonicalizes NSURLRequests.

  
## fix.m
// HACK: NSURLCache is using some weird comparator to check the NSURLRequest key and breaks
// caching with UIWebView, so we are canonicalizing the key.
//
// We set a static timeout because different timeouts will result in a miss.
- (NSURLRequest *) generateKeyForRequest:(NSURLRequest *)request {
    return [NSURLRequest requestWithURL:request.URL cachePolicy:request.cachePolicy timeoutInterval:60];
}
	// HACK: NSURLCache is using some weird comparator to check the NSURLRequest key and breaks
	// caching with UIWebView, so we are canonicalizing the key.
	//
	// We set a static timeout because different timeouts will result in a miss.
	- (NSURLRequest ) generateKeyForRequest:(NSURLRequest )request {
	return [NSURLRequest requestWithURL:request.URL cachePolicy:request.cachePolicy timeoutInterval:60];
	}