After I've scrolled a distance in a scroll view, I need to know what the distance is between a newly appearing child view and the top of the scroll view (not the top of the screen). How can I determine this distance?

To determine the distance between a newly appearing child view and the top of the scroll view, you can use the scroll transition and visual effect modifiers in SwiftUI. These modifiers allow you to track the position of elements within a scroll view and apply various effects based on their position.

For example, you can use the scroll transition modifier to get the y position of a shape and use it to offset, scale, fade, or blur an element as it gets to the top of the scroll view. This can help you determine the distance of a child view from the top of the scroll view.

Here is a relevant segment from the session "Create custom visual effects with SwiftUI":

"Here I'm taking the same y position of my shape and using it to offset scale fade and blur an element as it gets to the top of the scroll view. The scroll transition and visual effect modifiers are great ways to create custom scroll view effects." - Create custom visual effects with SwiftUI (00:05:08)

Additionally, you can use the value property of the scroll transition to determine how far off screen an image is, which can be adapted to measure the distance of any view from the top of the scroll view.

"I can use the value property to determine how far off screen my image is and use that for rotation, and if my view is fully on screen, the isidentity property will be true." - Create custom visual effects with SwiftUI (00:02:07)

For more detailed examples and advanced techniques, you can refer to the session "Create custom visual effects with SwiftUI".

After I've scrolled a distance in a scroll view, I need to know what the distance is between a newly appearing child view and the top of the scroll view (not the top of the screen). How can I determine this distance?

Relevant Sessions