Making Policy Decisions

You can make decisions about what web content to display in a WebView by implementing a policy delegate that conforms to the WebPolicyDelegate protocol.

The protocol is very flexible, allowing you to make a wide range of policy decisions. For example, you can implement a policy delegate to log URL requests, check for patterns you might not permit, block certain websites, block types of files, and even block IP addresses. The protocol provides the hooks for you to intercept requests—you implement the actual policy decisions.

For example, follow these steps to modify the MiniBrowser application located in /Developer/Examples/WebKit to ignore selected URLs:

1. Open MyDocument.nib using Interface Builder and set the WebView’s policyDelegate outlet to File’s Owner (the MyDocument instance).

2. Implement webView:decidePolicyForNavigationAction:request:frame:decisionListener: to filter the URL requests. In this example, URL requests with host names ending in company.com are ignored.

   - (void)webView:(WebView *)sender decidePolicyForNavigationAction:(NSDictionary *)actionInformation

   request:(NSURLRequest *)request frame:(WebFrame *)frame decisionListener:(id)listener {

   NSString *host = [[request URL] host];

   if ([host hasSuffix:@"company.com"])

   [listener ignore];

   else

   [listener use];

   }