I've over 20 projects, powering up more than 80,000 apps.
Here's the top 4 I've found most impactful in majority of Swift projects.
Inject
Hate recompiling times and restarting app, Swift Previews are not working?
Here's a better workflow helper that enables you to save hours of time each week, regardless if you are using UIKit, AppKit or SwiftUI.
Sourcery
A code generator for Swift language that allows you to get rid of repetitive code and create better architecture and developer workflows. It extends the language abstractions to allow you to generate boilerplate code automatically.
It's used in over 40,000 projects on both iOS and macOS and it powers some of the most popular and critically-acclaimed apps you have used (including Airbnb, Bumble, New York Times).
Difference
Easy diffing between two instances of same object.
Absolute must have if you do any kind of testing.
Lifetime Tracker
LifetimeTracker can surface retain cycle / memory issues right as you develop your application, and it will surface them to you immediately, so you can find them with more ease and before they hit your users.