Navigate a WebView

iphone, uiwebview, webview

Solution

You should enable your back button when `(webView.canGoBack == YES)`. You can do this in a delegate method like `webViewDidFinishLoad:`.

- (void)webViewDidFinishLoad {
  // Other stuff if necessary...

  // Could use hidden instead of enabled if you don't even want
  // the button to be visible
  backButtonItem.enabled = (webView.canGoBack);
}

Then, your "Touch Up Inside" action for the backButtonItem should look like this.

- (IBAction)backButtonClicked:(id)sender {
  [webView goBack];
}

Problem

With a webview is it possible to set up a simple 'Back' button (either in a navigation bar or a top toolbar) that doesn't show the back button on the first URL of the WebView - and only appearing on a second URL to get back to the first? Unless I'm getting getting this wrong, in a lot of hybrid native/web apps such as News apps, you often see news articles in a table (HTML page rather than a 'programmed in xcode' table) which hyperlink to article detail pages (again, HTML rather than natively coded) - what I can't figure, is how the detail page (2nd URL in webview) displays with a 'back button' but the table (1st URL in webview) doesn't have the button showing in these type of apps? Currently, I have a webview as described, with a 'back' bar button item in a toolbar at the top of screen (outlet as 'cangoback' for WebView) but the button is visible right from the start when there's no page to 'go back' to - What I've got simply is: Webview - 1st URL, HTML table - 'back' button shows, but isn't active (of course) Webview - 2nd URL, HTML detail page - 'back' button shows, and can go back. How do you get it to only appear on 2nd URL, or be HIDDEN on 1st URL? Regards Randy EDIT (25th November) Here's my h: ``` #import <UIKit/UIKit.h> #import "FilmnoirNavController.h" @interface FilmnoirViewController : UIViewController <UIWebViewDelegate> { IBOutlet UIWebView *webView; IBOutlet UIBarButtonItem *backButton; } @property (nonatomic, retain) UIWebView *webView; @property (nonatomic, retain) UIBarButtonItem *backButton; - (IBAction)backButtonClicked:(id)sender; @end ``` and here's my m: ``` #import "FilmnoirViewController.h" @implementation FilmnoirViewController @synthesize webView; @synthesize backButton; - (IBAction)backButtonClicked:(id)sender { [webView goBack]; } - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Initialization code } return self; } /* Implement loadView if you want to create a view hierarchy programmatically - (void)loadView { } */ /* If you need to do additional setup after loading the view, override viewDidLoad. */ - (void)viewDidLoad { NSString *urlAddress = @"http://www.filmsite.org/filmnoir.html"; //Create a URL object. NSURL *url = [NSURL URLWithString:urlAddress]; //URL Requst Object NSURLRequest *requestObj = [NSURLRequest requestWithURL:url]; //Load the request in the UIWebView. [webView loadRequest:requestObj]; } - (void)webViewDidFinishLoad { // Other stuff if necessary... // Could use hidden instead of enabled if you don't even want // the button to be visible backButton.enabled = (webView.canGoBack); } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview // Release anything that's not essential, such as cached data } - (void)dealloc { [webView release]; [super dealloc]; } @end ``` My IB layout: ``` Filmnoir View Controller (Film noir) > View >>Web View >>Tool Bar >>>Bar Button Item (Back) ``` Thought I had it with something like this to hide the backButton: ``` - (void)webViewDidFinishLoad { BOOL ableToGoBack = [webView canGoBack]; if (ableToGoBack == NO) { [backButton setHidden:YES]; } else { [backButton setHidden:NO]; } ``` but warning says a UIbarButton item may not respond to setHidden - and indeed it doesn't.

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