Clearing UIWebview cache

Question

I have used UIWebview to load a web page using loadRequest  method  when I leave that scene I call  self webView stopLoading   and release the webView   In activity monitor on first launch i have seen that the real memory increased by 4MB  and on multiple launches loading the real memory doesn t increase  It is increasing only once   I have checked the retain count of webview  It is proper i e   0  I think UIWebView is caching some data  How do I avoid caching or remove cached data  Or is there another reason for this

User · Answer

You can disable the caching by doing the following:

NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:0 diskPath:nil];
[NSURLCache setSharedURLCache:sharedCache];
[sharedCache release];

ARC:

NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:0 diskPath:nil];
[NSURLCache setSharedURLCache:sharedCache];

User · Answer

I could not change the code  so I needed command line for testing purpose and figured this could help someone   Application specific caches are stored in   Library Caches  lt bundle-identifier-of-your-app gt   so simply remove as below and re-open your application  rm -rf    Library Caches com mycompany appname

User · Answer

I am loading html pages from Documents and if they have the same name of css file UIWebView it seem it does not throw the previous css rules  Maybe because they have the same URL or something   I tried this   NSURLCache  sharedCache     NSURLCache alloc  initWithMemoryCapacity 0 diskCapacity 0 diskPath nil    NSURLCache setSharedURLCache sharedCache    sharedCache release     I tried this       NSURLCache sharedURLCache  removeAllCachedResponses     I am loading the initial page with   NSURLRequest  appReq    NSURLRequest requestWithURL appURL cachePolicy NSURLRequestReloadIgnoringLocalCacheData timeoutInterval 20 0     It refuses to throw its cached data  Frustrating   I am doing this inside a PhoneGap  Cordova  application  I have not tried it in isolated UIWebView   Update1  I have found this  Changing the html files  though seems very messy

User · Answer

My educated guess is that the memory use you are seeing is not from the page content  but rather from loading UIWebView and all of it s supporting WebKit libraries   I love the UIWebView control  but it is a  heavy  control that pulls in a very large block of code   This code is a large sub-set of the iOS Safari browser  and likely initializes a large body of static structures

User · Answer

I actually think it may retain cached information when you close out the UIWebView  I ve tried removing a UIWebView from my UIViewController  releasing it  then creating a new one  The new one remembered exactly where I was at when I went back to an address without having to reload everything  it remembered my previous UIWebView was logged in    So a couple of suggestions     NSURLCache sharedURLCache  removeCachedResponseForRequest NSURLRequest     This would remove a cached response for a specific request  There is also a call that will remove all cached responses for all requests ran on the UIWebView     NSURLCache sharedURLCache  removeAllCachedResponses     After that  you can try deleting any associated cookies with the UIWebView   for NSHTTPCookie  cookie in   NSHTTPCookieStorage sharedHTTPCookieStorage  cookies          if   cookie domain  isEqualToString someNSStringUrlDomain                NSHTTPCookieStorage sharedHTTPCookieStorage  deleteCookie cookie             Swift 3      Remove all cache  URLCache shared removeAllCachedResponses       Delete any associated cookies      if let cookies   HTTPCookieStorage shared cookies       for cookie in cookies           HTTPCookieStorage shared deleteCookie cookie

User · Answer

After various attempt  only this works well for me  under ios 8    NSURLCache  cache     NSURLCache alloc  initWithMemoryCapacity 1 diskCapacity 1 diskPath nil    NSURLCache setSharedURLCache cache

User · Answer

Swift 3      Remove all cache  URLCache shared removeAllCachedResponses       Delete any associated cookies      if let cookies   HTTPCookieStorage shared cookies       for cookie in cookies           HTTPCookieStorage shared deleteCookie cookie

User · Answer

For swift 2 0   let cacheSizeMemory   4 1024 1024     4MB let cacheSizeDisk   32 1024 1024     32MB let sharedCache   NSURLCache memoryCapacity  cacheSizeMemory  diskCapacity  cacheSizeDisk  diskPath   nsurlcache   NSURLCache setSharedURLCache sharedCache

User · Answer

Don t disable caching completely  it ll hurt your app performance and it s unnecessary  The important thing is to explicitly configure the cache at app startup and purge it when necessary    So in application DidFinishLaunchingWithOptions  configure the cache limits as follows   -  BOOL application  UIApplication   application didFinishLaunchingWithOptions  NSDictionary   launchOptions          int cacheSizeMemory   4 1024 1024     4MB     int cacheSizeDisk   32 1024 1024     32MB     NSURLCache  sharedCache     NSURLCache alloc  initWithMemoryCapacity cacheSizeMemory diskCapacity cacheSizeDisk diskPath   nsurlcache         NSURLCache setSharedURLCache sharedCache               other launching code     Once you have it properly configured  then when you need to purge the cache  for example in applicationDidReceiveMemoryWarning or when you close a UIWebView  just do     NSURLCache sharedURLCache  removeAllCachedResponses     and you ll see the memory is recovered  I blogged about this issue here  http   twobitlabs com 2012 01 ios-ipad-iphone-nsurlcache-uiwebview-memory-utilization

[ios] Clearing UIWebview cache

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