Currently ChatHeads are positioned based on a simple rule (move to the edge of the screen based on the release point). But Facebook built a more sophisticated way of interaction. The whole system is based on real physics (e.g. you can throw a ChatHead from one edge to the other, which is definitely done by calculating the physics).
[...] “We built an entire physics engine that everything runs on,” he says. “It’s more like your app is built like a game, as opposed to built with app components.” [...] Source <- maybe that's only related to Android.
I'm not sure if the animations are done by a physics engine or by "simply" calculating the animation path based on gravity and mass and the animation itself is done by CoreAnimation.
Currently ChatHeads are positioned based on a simple rule (move to the edge of the screen based on the release point). But Facebook built a more sophisticated way of interaction. The whole system is based on real physics (e.g. you can throw a ChatHead from one edge to the other, which is definitely done by calculating the physics).
[...] “We built an entire physics engine that everything runs on,” he says. “It’s more like your app is built like a game, as opposed to built with app components.” [...] Source <- maybe that's only related to Android.
I'm not sure if the animations are done by a physics engine or by "simply" calculating the animation path based on gravity and mass and the animation itself is done by CoreAnimation.