Open the Twitter App Directly from Safari in iOS 6
The next time you’re browsing the web and come across a link that points to Twitter, you can immediately jump to the Twitter app if you want to. This is a new ability included in iOS 6 onward.
To access the feature, pull down from the top of Safari when a Twitter link is opened, and you’ll see a menu item that shows if Twitter is available or not, an option to install the app if it’s not, and the “Open” button shown in the screenshot. Tapping that Open button is what immediately launches Twitter, passing the current link to the Twitter app. This is great if you’ve come across a link to a tweet and decided you want to follow the user, or just explore their timeline more through the official Twitter app.
That type of behavior works with some other apps and content as well in the newest versions of mobile Safari, including PDF’s, ebooks, and epubs.