What are the differences of ScrollView and UIScrollView?

The differences between ScrollView in SwiftUI and UIScrollView in UIKit are highlighted in several WWDC sessions. Here are some key points:

1. Declarative vs. Imperative:

   • ScrollView (SwiftUI): SwiftUI uses a declarative syntax, meaning you describe what you want the UI to look like and let the framework handle the details.
   • UIScrollView (UIKit): UIKit uses an imperative approach, where you explicitly manage the state and behavior of the UI components.

2. Modifiers and Customization:

   • ScrollView (SwiftUI): SwiftUI provides various modifiers to customize the behavior and appearance of scroll views. For example, you can use the scrollTransition modifier to create custom scroll effects, such as parallax or carousel effects (Create custom visual effects with SwiftUI).
   • UIScrollView (UIKit): Customization in UIScrollView often requires more manual setup and handling, such as implementing delegate methods to respond to scrolling events.

3. Programmatic Control:

   • ScrollView (SwiftUI): SwiftUI offers more programmatic control over scroll views, including new scroll positions and the ability to programmatically stop scrolling or control content alignment (What’s new in SwiftUI).
   • UIScrollView (UIKit): While UIScrollView also allows programmatic control, it typically involves more boilerplate code and manual state management.

4. Interoperability:

   • ScrollView (SwiftUI): SwiftUI scroll views can be easily integrated with other SwiftUI components and benefit from SwiftUI's declarative nature.
   • UIScrollView (UIKit): UIKit scroll views can be used within SwiftUI using UIViewRepresentable, but this adds complexity and reduces the benefits of SwiftUI's declarative syntax.

5. New Features in SwiftUI:

   • SwiftUI has introduced new scroll view modifiers specific to tvOS 18, such as onScrollVisibilityChange and scrollTargetBehavior, which enhance the customization and behavior of scroll views (Migrate your TVML app to SwiftUI).

For a deeper dive into these differences, you can refer to the following sessions:

• What’s new in SwiftUI
• Create custom visual effects with SwiftUI
• Migrate your TVML app to SwiftUI