To access your Twitter QR code, you'll need the official Twitter app for iOS. In the app, go to your profile, tap on the gear icon, and select the "QR Code" option to generate your own personal QR code or scan someone else's code.
Scanning a QR code is as simple as using the iPhone's camera to either scan from a secondary screen or an image you've saved to the camera roll. You can follow MacRumors on Twitter by scanning the below code with your iPhone and the Twitter app.
QR codes were first made popular by Snapchat as a quick way to find your friends without having to search for them, but they may not be as popular on Twitter because the QR code settings are buried so deeply within the app.
Twitter's QR codes are currently rolling out to users and may not be immediately available for everyone.
Twitter for iOS can be downloaded from the App Store for free. [Direct Link]