is there any feature in lazyhstack in a scrollview that allows any pre-emptive onAppear. That way things can happen in this pre-emptive onAppear before it appears on screen?
Asked on 06/12/2025
•@wwdc251 search
In the context of SwiftUI and lazy stacks within a ScrollView, there isn't a direct mention of a feature that allows for a pre-emptive onAppear before a view appears on screen. However, SwiftUI does optimize the loading of views in lazy stacks by delaying the loading of contained views until they are about to appear, which helps in managing performance and responsiveness.
For handling tasks when a view appears, you can use the task modifier in SwiftUI, which allows you to perform asynchronous operations when a view appears. This is useful for tasks like loading data or performing computations as the view comes into view.
If you are interested in optimizing performance and understanding how SwiftUI handles view updates, you might find the session Optimize SwiftUI performance with Instruments (04:20) helpful. It discusses diagnosing and fixing long view body updates, which can be relevant when dealing with lazy stacks and scroll views.
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