Open a facebook link by native Facebook app on iOS

Just use https://graph.facebook.com/(your_username or page name) to get your page ID and after you can see all the detain and your ID

after in your IOS app use :

 NSURL *url = [NSURL URLWithString:@"fb://profile/[your ID]"];
 [[UIApplication sharedApplication] openURL:url];

Here are some schemes the Facebook app uses, there are a ton more on the source link:

Example

NSURL *url = [NSURL URLWithString:@"fb://profile/<id>"];
[[UIApplication sharedApplication] openURL:url];

Schemes

fb://profile – Open Facebook app to the user’s profile

fb://friends – Open Facebook app to the friends list

fb://notifications – Open Facebook app to the notifications list (NOTE: there appears to be a bug with this URL. The Notifications page opens. However, it’s not possible to navigate to anywhere else in the Facebook app)

fb://feed – Open Facebook app to the News Feed

fb://events – Open Facebook app to the Events page

fb://requests – Open Facebook app to the Requests list

fb://notes – Open Facebook app to the Notes page

fb://albums – Open Facebook app to Photo Albums list

If before opening this url you want to check wether the user fas the facebook app you can do the following (as explained in another answer below):

if ([[UIApplication sharedApplication] canOpenURL:nsurl]){
    [[UIApplication sharedApplication] openURL:nsurl];
}
else {
    //Open the url as usual
}

Source

http://wiki.akosma.com/IPhone_URL_Schemes#Facebook

To add yonix’s comment as an answer, the old fb://page/… URL no longer works. Apparently it was replaced by fb://profile/…, even though a page is not a profile.