Yahoo has announced on its official blog (via The Next Web) that it will begin rolling out second sign-in verification for its services along with "App Passwords", which act as one-time temporary passwords that a user can enter to authorize Yahoo accounts with native Yahoo apps for iOS devices.
An App Password is a temporary password that you can enter into our native iOS and Android apps for added protection. It’s a way that you can authorize a device to access your Yahoo apps.
Simply go into your account settings, turn on second sign-in verification, and then generate the one-time app password. Once you do, you can enter the password your mobile app, and it’s as simple as that. Your device will be logged-in, so you won’t have to go through this step again.
Adding other devices will require users to generate new App Passwords, and the users can revoke account access for each individual app and device through Yahoo’s built-in control panel on its website.
Yahoo has updated and launched a number of iOS services in the past year, including releasing its own standalone iPhone weather app along with a dedicated mail app for the iPad, and redesigning its Tumblr app after acquiring the blogging service. Apple and Yahoo were also said to be in talks over a "deeper iPhone partnership" earlier this year.