Delegate method for when caching logic is running without server cues

Originator:daniel
Number:rdar://11541572 Date Originated:5/26/2012
Status:Closed Resolved:Yes
Product:Developer Tools Product Version:iOS 5.1/OS X 10.7.4
Classification:Enhancement Reproducible:N/A
 
26-May-2012 05:54 PM Daniel Pasco:
Summary:
When NSURLRequestUseProtocolCachePolicy is used for an NSURLRequest (the default), the frameworks use an apparently undocumented, very long-lived caching policy if expiration details are not explicitly provided by the server.

It would be very nice in this situation if a delegate method on NSURLConnection could be used to communicate to the app that it will be caching the data without server guidelines. In some cases it may be better for the application to disable caching and fetch data directly.

This would be preferable to disabling local caching through the use NSURLRequestReloadIgnoringLocalCacheData, since that would totally ignore it when servers provide valid expiration information and could potentially result in a very large amount of server traffic.

This could conceivably be done by decorating the NSCachedURLResponse passed to the - (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse with expiration information.

Steps to Reproduce:
N/A

Expected Results:
N/A

Actual Results:
N/A

Regression:
N/A

Notes:
We recently shipped an application using NSURLRequestUseProtocolCachePolicy. The server was not configured to provide expiration information in its response headers and users ended up missing time-critical events.

Comments

There is sufficient information contained in - connection:willCacheResponse: to make this determination. See http://blackpixel.com/blog/1659/caching-and-nsurlconnection/ for details

By daniel at May 28, 2012, 12:57 a.m. (reply...)

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