clear cookies in iOS

gistfile1.m

- (void)clearCookies{
  NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
  for (NSHTTPCookie *each in cookieStorage.cookies) {
    if ([[[each properties] objectForKey:NSHTTPCookieDomain] isEqualToString:@".douban.com"] &&
        [[[each properties] objectForKey:NSHTTPCookieName] isEqualToString:@"bid"]) {
        [cookieStorage deleteCookie:each];
        NSDictionary* dic = [each properties];
        [dic setValue:@"" forKey:NSHTTPCookieValue];
        NSHTTPCookie* cookie = [NSHTTPCookie cookieWithProperties:dic];
        [cookieStorage setCookie:cookie];
    }
  }
}