Re: WebKit Caching
Re: WebKit Caching
- Subject: Re: WebKit Caching
- From: Adam Thorsen <email@hidden>
- Date: Fri, 10 Apr 2009 12:18:24 -0700
Jeff,
The test case is this:
Create an html page that requires a javascript file. Ensure that the
javascript file has not been modified for at least an hour.
Load a page that includes a javascript file into a webview.
Now change the javascript file and reload the contents of the webview.
Any changes made to the javascript file will not be evident.
Now quit the app and restart. Load the contents of the html page.
The changes should show up.
Alter the .js file again.
Reload the page and the changes should be reflected.
I can provide code that demonstrates this if desired.
Also, I have posted my issue on the webkit-dev mailing list.
Thanks,
-Adam
On Apr 10, 2009, at 11:27 AM, Jeff Johnson wrote:
If that's true, it sounds like a WebKit bug. Do you have a test case?
Also, just noticing the mailing list we're on. WebKit developers and
others familiar with WebKit development tend to hang out on the
webkitsdk-dev list, so you might have better luck with your question
there.
-Jeff
On Apr 10, 2009, at 1:09 PM, Adam Thorsen wrote:
Jeff,
Thanks for the response. These techniques do not appear to affect
how WebKit caches javascript resources.
This is what I tried:
WebPreferences *prefs = [webView preferences];
[prefs setUsesPageCache:NO];
and
WebPreferences *prefs = [webView preferences];
[prefs setPrivateBrowsingEnabled:YES];
Thanks,
-Adam
On Apr 10, 2009, at 9:58 AM, Jeff Johnson wrote:
Adam,
I think that -[WebPreferences setUsesPageCache:] should work. -
[WebPreferences setPrivateBrowsingEnabled:] will also have this
effect, though it may be more than you want.
-Jeff
On Apr 10, 2009, at 11:27 AM, Adam Thorsen wrote:
I would like to prevent a WebKit WebView from caching certain
content. I've attempted to prevent this using several
approaches, including:
1. Overriding the NSURLCache cachedResponseForRequest and
cachedResponse forRequest methods
2. Handling -(NSURLRequest *)webView:(WebView *)sender resource:
(id) willSendRequest:(NSURLRequest *) redirectResponse:
(NSURLResponse *) fromDataSource:(WebDataSource *)dataSource
a) tried setting the cache policy to
NSURLRequestReloadIgnoringCacheData, among other settings
b) tried appending a random string onto the end of the
resource url before passing it along (i.e. something like http://blah.com/file.js?23234234234)
3. Clearing the cache by setting the shared url cache (via
NSURLCache ) and calling removeAllCachedResponses before each
page load.
None of these approaches have any effect on what the webview
instance decides to cache. Based on its behavior, I believe that
on initial page load it checks the last-modified value in each
response header and caches resources in memory that have not been
modified within a certain period of time. Recently modified
files (within the past few minutes) are not cached.
My ultimate goal is simply to prevent the webview from caching,
and I am open to any suggestions on how to do that. However,
based on my above hypothesis about how WebKit handles caching
internally, I believe that if I could rewrite the response
headers such that last-modified is always a recent value, I could
prevent WebKit from caching.
Currently I can view the response header by implementing:
- (void)webView:(WebView *)sender resource:(id)identifier
didReceiveResponse:(NSURLResponse *)response fromDataSource:
(WebDataSource *)dataSource
and calling allHeaderFields on the response. However, there
appears to be no way to modify the response before sending it on
to the webview for display. Are there any suggestions on how to
do this?
Thanks,
-Adam
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