Let’s talk about view controllers. Right off the hop, stop making a mess of your view controllers and start putting your code in logical places – view controllers are for views, and views only. It’s very tempting to throw all sorts of logic into a view controller, but when we separate concerns, we write code that’s easier to understand and easier to reuse.
There are handfuls of responsibilities we can dump into a view controller: data fetching, data transformation, user input, model-view binding, model mutation, animations, and navigation flow, just to name a few. But, we shouldn’t house all of these responsibilities in one place; otherwise, we’re working with a confusing and unwieldy view controller.