Prevent caching of .css files in UIWebView loaded from disk

Question

In the iPad project I'm working on I've got a UIWebView inside of the app which displays a .html file which links to a .css file, i.e.

<link rel="stylesheet" href="style.css" type="text/css">

These files are stored locally on the iPad but are fetched from a remote server. I've noticed that UIWebView caches the .css file more or less indefinitely, and refuses to load the new file whenever I change it. I've once changed the name of the file just to get it to reset, but that's unacceptable in the long run.

Is there a way to prevent caching of the CSS file in a UIWebView? Or even better, is there a way to say when to cache and when not to?

riwalk · Accepted Answer · 2010-08-23 16:36:45Z

17

Yes.

Change your line to this:

<link rel="stylesheet" href="style.css?version=1" type="text/css">

Every time that you update the stylesheet, change the version. The browser will think that it is a different page because of the query string, and your server will ignore it.

If you are using a server side language such as PHP, you can also do the following:

<link rel="stylesheet" href="style.css?version=<?php echo time(); ?>" type="text/css">

This will change the version every time you refresh, thus stopping all caching.

answered Aug 23, 2010 at 16:36

riwalk

14.3k6 gold badges54 silver badges68 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Kalle Over a year ago

That's a neat idea, for sure! But if I say I have something like 15 .html files which each have their own <link> line, this would still not solve the problem. If it was only one file...

riwalk Over a year ago

Having 15 files with the exact same <link> tag is a sign of duplication in your code. Remove duplication, then changing the version will be trivial.

Michael Kessler Over a year ago

no server side languages on local files in iPad - only HTML, CSS and JavaScript. @Kelle, you might use @Stargazer712's time suggestion from Objective-C. Something like this:

[htmlString stringByReplacingOccurrencesOfString:@"style.css" withString:[NSString stringWithFormat:@"style.css?time=%@", [[NSDate date] description]]

Kalle Over a year ago

Stargazer712: why is having multiple .html files which each link to the same CSS file duplication in code? Duplication would be putting the CSS straight into the HTML file in a style tag. This is more like inheriting from the same class in a bunch of objects. Michael: yeah, I went with that route in fact. Thanks for the input, both of you.

riwalk Over a year ago

You answered your own question. Making a change such as this requires that you change 15 files. That is duplication. It doesn't sound like you have access to a server-side language, so this may not have a quick remedy, but if you do have access to a server-side language, you need to look into using templates or master pages (depending on the language of course).

|

jamesmoschou · Accepted Answer · 2014-01-23 01:31:11Z

1

The better way that keeps your HTML markup and iOS code isolated is

[[NSURLCache sharedURLCache] removeCachedResponseForRequest:yourRequest];

answered Jan 23, 2014 at 1:31

jamesmoschou

1,1738 silver badges15 bronze badges

1 Comment

Erik Reppen Over a year ago

[[NSURLCache sharedURLCache] removeAllCachedResponses]; That's to clear all. See ToddH's answer here for a way to also limit the amount of memory the caching is allowed to use. Really helps with webview perf. stackoverflow.com/questions/5468553/clearing-uiwebview-cache

Collectives™ on Stack Overflow

Prevent caching of .css files in UIWebView loaded from disk

2 Answers 2

7 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

7 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related