Trapping non-standard URLs

gistfile1.m

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    NSString *scheme = [[[request URL] scheme] lowercaseString];
    
    
    // Allow standard URLs through
    NSSet *stdSchemes = [NSSet setWithObjects:@"http", @"file", nil];
    if ([stdSchemes containsObject:scheme]) {
        return YES;
    }
    
    
    // We do something with the special RB scheme
    if ([scheme isEqualToString:@"rb"]) {
        if (!delegate) {
            return NO;
        }
        
        NSString *event = [[[request URL] host] lowercaseString];

        if ([event isEqualToString:@"scrolled.bottom"]) {
            if ([delegate respondsToSelector:@selector(webPageScrolledToBottom:)]) {
                dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
                    [delegate webPageScrolledToBottom:_fileName];
                });
            }
        }
    }
    
    return NO;
}