Create a sliding animation with Swift

I've made an app where using a slide gesture will take you from the current view to the next, however there is no animation. When you slide it just instantly replaces the screen with the new view. I want there to be a sliding animation and also want the animation to be in time with your hand as you slide across instead of just an "automatic" sliding animation if you were to swipe. Snapchat would be a good example of what I'd like to achieve, where as you slide between views the current view goes to the next. Any thing will help!