I have a function, that open PDF file in WebView in fullscreen mode.

How to add "Done" button, that can close WebView?

```
- (IBAction)openPDF:(id)sender {
    UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectMake(0,0,self.view.bounds.size.width,self.view.bounds.size.height)];

    webView.contentMode = UIViewContentModeScaleAspectFit;

    NSString *path = [[NSBundle mainBundle] pathForResource:@"pdf" ofType:@"pdf"];
    NSURL *targetURL = [NSURL fileURLWithPath:path];
    NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];

    CGRect frame = webView.frame;
    webView.scalesPageToFit = YES;
    webView.frame = frame;

    [webView loadRequest:request];

    [self.view addSubview:webView];
}

```