App / Backend-Architecture: How do Snapchat stories load?

Question

Simple question. How do Snapchat stories load so fast, and even when I “skip” an item, is the next always ready?

Snapchat stories is a mixture of images and videos, whenever a screen is listened to, the next item starts instantly, regardless of whether it is an image or video. I have never seen a delay in the application, and I'm curious

How do they do it? Do they cache all content after launching the application (unlikely)? Do they constantly download upcoming items while watching a story? Do they download everything when I use history? I don’t understand the “magic” behind the flawless flow of content. Also: What does the backend provide? List of resources?

Does anyone know how they do this? Other applications, such as Yeti or Fleek, pretty much do the same thing, executed in the same flawless order. I am a pretty decent iOS developer, but I have no idea about the method that is used here.

Answer 1

The use case allows you to create backgrounds on the side of the application and cache on the back panel.

So, how would I do this, something like this:

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