UIKit is Apple's original framework for building iOS interfaces. SwiftUI is where new apps usually start, but a huge number of production apps are still built on UIKit, and many SwiftUI apps reach into it for features SwiftUI doesn't cover yet. Knowing the basics makes you far more useful on a real team.
You'll start with views and view controllers, then lay out screens with Auto Layout. Next come the workhorses of UIKit apps, table views and collection views, followed by navigation controllers, tab bars, and modals. You'll finish by seeing how UIKit and SwiftUI can work together in the same app.
Several of these videos are a year or two old, but the core UIKit concepts haven't changed. When you're ready, continue on to Networking & Concurrency.
Meet the UIKit framework and set up your first simple app using buttons and labels.
The essentials of creating responsive, adaptable layouts with Auto Layout.
How table views and collection views display data in UIKit.
Work with UITableView and UITableViewCell in Swift 5, including custom cells.
Every way to move between screens in UIKit, from navigation controllers and tab bars to modals.
See how UIKit components can be brought into a SwiftUI app.