GeometryReader in SwiftUI ScrollView causes weird behaviour and random offset

Question

Im trying to create a ScrollView that in turn contains a GeometryReader (Explicitly not the other way around). The GeometryReader should contain an (image) with a fixed width and height. However when doing this, the ScrollView pushes the view "above" the screen, it seems like it's applying some random vertical offset.

var body: some View {
    ScrollView {
        GeometryReader { geometry in
            Image("hp")
                .resizable()
                .aspectRatio(contentMode: .fill)
                .frame(width: geometry.size.width, height: 400)
                .clipped()
        }
    }
}

When removing the GeometryReader and just inserting the image it works fine.

Can somebody help?

Edit: Found a solution. I achieved the desired behaviour by telling the image that it should be as high and wide as the inner geometry reader. Then i'm setting the inner geometry reader

var body: some View {
    GeometryReader { outerGeometry in
        ScrollView {
            VStack {
                GeometryReader { innerGeometry in
                    Image("hp")
                        .resizable()
                        .aspectRatio(contentMode: .fill)
                        .frame(width: innerGeometry.size.width,
                        height: innerGeometry.size.height)
                        .offset(y: innerGeometry.frame(in: .global).minY/7)
                        .clipped()
                }
                    .frame(width: outerGeometry.size.width, height: 300)
            }
        }
    }
}

shim · Accepted Answer · 2022-04-26 14:37:18Z

26

Just try to put ScrollView inside GeometryReader and not vice versa:

// ...
    var body: some View {
        
        GeometryReader { geometry in
            
            ScrollView {
                Image("hp")
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .frame(width: geometry.size.width, height: 400)
                    .clipped()
            }
        }
            
    }
// ...

and the result should be:

edited Apr 26, 2022 at 14:37

shim

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answered Nov 21, 2019 at 3:12

Hrabovskyi Oleksandr

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Comments

jaume · Accepted Answer · 2021-05-24 01:23:19Z

9

GeometryReader, if placed as you did, provides the size not of ScrollView itself, but of "Content View" in which image is placed. "Content View" of ScrollView is bigger than screen size, to allow spring effect at the edges, when one scrolls more than a scrolling document size.

The correct usage is in @Александр_Грабовский's answer.

edited May 24, 2021 at 1:23

jaume

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answered Nov 21, 2019 at 3:27

Asperi

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