ViewController slide animation

Question

I want to create an animation like the iOS app facebook at tabswitch^[1]. I have already tried to develop some kind of animation, the problem that

Answer 1

I've never seen Facebook so I don't know what the animation is. But you can have any animation you like when a tab bar controller changes its tab (child view controller), coherently and without any hacks, using the built-in mechanism that Apple provides for adding custom animation to a transition between view controllers. It's called custom transition animation.

Apple first introduced this mechanism in 2013. Here's a link to their video about it: https://developer.apple.com/videos/play/wwdc2013/218/

I immediately adopted this in my apps, and I think it makes them look a lot spiffier. Here's a demo of a tab bar controller custom transition that I like:

The really cool thing is that once you've decided what animation you want, making the transition interactive (i.e. drive it with a gesture instead of a button click) is easy:

Now, you might be saying: Okay, but that's not quite the animation I had in mind. No problem! Once you've got the hang of the custom transition architecture, changing the animation to anything you like is easy. In this variant, I just commented out one line so that the "old" view controller doesn't slide away:

So let your imagination run wild! Adopt custom transition animations, the way that iOS intends.