Twitter updated its Vine app for iOS today with features designed to improve taking videos and help users explore them. The updates, which come about two weeks after Instagram updated to include video, show Vine continuing to build out its feature set amid signs that Instagram is blunting its momentum.

The updates, some of which Vine had hinted about, include a redesigned camera that includes a grid and a focusing tool. A "ghost" tool lets users line up their next shot by overlaying a ghosted image of the previous take. Users can also now "revine," posting Vines taken by users directly into their own feeds. But the update is missing one big camera update that Instagram has and Vine users have been requesting: an ability to undo the last shot.

On iOS today and coming to the Android app next week

The other Vine updates are focused on helping users find other interesting creators and videos. The company introduced 15 channels into the app, which organize videos into themes including comedy, music, and nature. Each topic comes along with its own "popular" feed for users to see which videos have been hits. And Vine will begin highlighting individual users with "On the Rise," a section that features up-and-coming creators.

There's also a new privacy feature: Vine users can now protect their posts, meaning that only approved followers can see them unless the user chooses to share them on Twitter or Facebook. An update rolling out now will bring protected posts to the Android app, Vine said. "Other features" are coming to the Android app next week, the company said, without specifying which ones.

The update is now available in the App Store.