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A Facebook Like button for native iOS apps

branch: master
README.md

FacebookLikeView

FacebookLikeView is a Facebook Like button for native iOS apps.

It integrates with the Facebook iOS SDK so that authenticated users can Like with a single tap, and unauthenticated users are prompted with the standard authentication dialog.

FacebookLikeView is not officially supported by Facebook, and it requires your application to use the in-app authentication dialog rather than single sign-on via Safari or the Facebook app.

To see FacebookLikeView in action, build the included FacebookLikeViewDemo project.

Getting started

  1. If you haven't already installed the Facebook iOS SDK, add the files in the FBConnect directory to your Xcode project.
  2. Add the files in the FacebookLikeView directory to your Xcode project.
  3. Instantiate a FacebookLikeView programmatically or in a nib.
  4. Set the URL to be liked, plus any Like button attributes you'd like to customize. Make sure the layout you choose fits within the view's bounds.

    _facebookLikeView.href = [NSURL URLWithString:@"http://www.yardsellr.com"];
    _facebookLikeView.layout = @"button_count";
    _facebookLikeView.showFaces = NO;
    
  5. Set a delegate that implements facebookLikeViewRequiresLogin:. Your implementation should call -[Facebook authorize:delegate:], and then -[FacebookLikeView load] once login is complete.

    _facebookLikeView.delegate = self;
    
    ...
    
    - (void)facebookLikeViewRequiresLogin:(FacebookLikeView *)aFacebookLikeView {
        [_facebook authorize:[NSArray array] delegate:self];
    }
    
    - (void)fbDidLogin {
        [_facebookLikeView load];
    }
    
  6. Finally, call -[FacebookLikeView load] before you display the view. You should also call this method any time the user signs in or out of Facebook, and after modifying any of the FacebookLikeView's properties.

More delegate methods

You may want to be notified when the Like button is used. In that case, implement these optional FacebookLikeViewDelegate methods:

- (void)facebookLikeViewDidLike:(FacebookLikeView *)aFacebookLikeView;
- (void)facebookLikeViewDidUnlike:(FacebookLikeView *)aFacebookLikeView;

To avoid showing the Like button before it's completely rendered, you can hide the FacebookLikeView until this delegate method is called:

- (void)facebookLikeViewDidRender:(FacebookLikeView *)aFacebookLikeView;

How it works

FacebookLikeView uses a web view to host the same Like button XFBML as would be used on a web page.

Since the web view shares cookies with all other web views in your app, a user that authenticates through Facebook's in-app dialog is also authenticated to use the Like button. The web view does not share cookies with Safari or the Facebook app, so FacebookLikeView monkeypatches FBConnect to never use those apps for authentication.

Unlike a plain web view, FacebookLikeView does not follow redirects. If redirected to the Facebook login page, it ignores the redirect and calls the delegate method facebookLikeViewRequiresLogin: so that you may present a dialog instead.

FacebookLikeView monitors Like/Unlike events using FB.Event.subscribe. When one of those events fires, a bit of JavaScript running inside the web view encodes the event into a URL request that is intercepted by native code, which then calls the appropriate delegate method.

Caveats

FacebookLikeView is not supported by Facebook and is subject to break when changes are made in the Like button's implementation.

FacebookLikeView is also not necessarily compatible with future versions of the Facebook iOS SDK. To ensure compatibility, use the SDK snapshot contained in the FBConnect directory.

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