Release memory/cookie/cache from UIWebView once closed - ios

Question

I have a UIViewController which contains a UIWebView.
i login to a website for say facebook using the UIWebview in the UIViewController then i click on done, which dismiss the view controller, which i suppose will release the view controller. but when i open the UIWebview again (without exiting the app and also even after terminating the app) the webpage is still log into Facebook after the web view loads. How should i release the web view so that every time i click on done and return back to the web view, the web view will always be like "brand new" not log-on to any website that i had previously log-on to.
- (void)viewDidLoad{
NSLog(#"webView viewDidLoad called");
appDelegate = (LoginDBAppDelegate *)[[UIApplication sharedApplication] delegate];
loginObj = [appDelegate.loginArray objectAtIndex:currentSelectedRow];
myWebView.delegate = self;
[super viewDidLoad];
[self showWebView];
}
-(void)showWebView{
NSLog(#"webView showWebView called");
NSURL *url = [NSURL URLWithString:loginObj.loginURL];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[myWebView loadRequest:request];
}
-(IBAction)done_Clicked:(id)sender{
NSLog(#"webView Done_Clicked");
//dismiss the controller
[self.navigationController dismissModalViewControllerAnimated:YES];
}
-(void)dealloc{
[myWebView release];
myWebView.delegate = nil;
[activity release];
[urlTextField release];
[super dealloc];
}
I have tried this but it didn't work:
-(IBAction)done_Clicked:(id)sender{
NSLog(#"webView Done_Clicked");
[[NSURLCache sharedURLCache] removeAllCachedResponses];
[myWebView stringByEvaluatingJavaScriptFromString:#"var body=document.getElementsByTagName('body')[0];body.style.backgroundColor=(body.style.backgroundColor=='')?'white':'';"];
[myWebView stringByEvaluatingJavaScriptFromString:#"document.open();document.close()"];
//dismiss the controller
[self.navigationController dismissModalViewControllerAnimated:YES];
}
I have also tried this without any success:
- (void) viewDidDisappear:(BOOL)animated {
NSLog(#"webView viewDidDisappear called");
[super viewDidDisappear:animated];
[self.myWebView removeFromSuperview];
self.myWebView.delegate = nil;
self.myWebView = nil;
[myWebView release];
}

Answer 1

Got the answer from someone on the forum, so credit to him...
Place this code in viewDidLoad
//Set Cache
NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:0 diskPath:nil];
[NSURLCache setSharedURLCache:sharedCache];
//Clear All Cookies
for(NSHTTPCookie *cookie in [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookies]) {
//if([[cookie domain] isEqualToString:someNSStringUrlDomain]) {
[[NSHTTPCookieStorage sharedHTTPCookieStorage] deleteCookie:cookie];
}