In late September, Google released Android Wear 2.0 Developer Preview 3, while also confirming the platform would not see a public launch until early 2017.

That early 2017 launch means more time for Google to roll out features, and gives developers more time to prepare apps for the smartwatch platform. To help with that effort, Google has rolled out Android Wear 2.0 Developer Preview 4, which not only adds a few key features, but also brings back one oft-requested feature from Android Wear 1.0.

First, the new Developer Preview welcomes “Seamless Authentication.” With it, users will be able to tap a button on their Android Wear-based device’s display, and then an authentication screen will show up on their phone, which should make it easier to log into apps and services.

In-app billing is also supported in Android Wear 2.0 now. With it, developers can more easily monetize their apps, so that users can simply tap in a 4-digit Google Account PIN to securely purchase something right from the smartwatch.

Swipe-to-Dismiss has also returned:

• Activities now automatically support swipe-to-dismiss. Swiping an activity from left to right will result in it being dismissed and the app will navigate down the back stack.
• New Fragment and View support. Developers can wrap the containing views of a Fragment or Views in general in the new SwipeDismissFrameLayout to implement custom actions such as going down the back stack when the user swipes rather than exiting the activity.
• Hardware button now maps to “power” instead of “back” which means it can no longer be intercepted by apps.

There are other new additions to Developer Preview 4, which you can see through the source link below.