Apple has acquired PullString, the startup behind the voice technology powering the interactive "Hello Barbie" doll Mattel released in 2015. PullString, previously known as ToyTalk, was founded back in 2011 by former Pixar employees. Its AI platform gave its partner companies and clients a way to create digital and physical characters and voice apps that can communicate with people. Hello Barbie was one of those -- an interactive Thomas The Tank Engine toy was another. The company previously launched software that makes it easy even for non-technical pros to create Alexa apps of their own, as well.