4

I am trying to create a view in SwiftUI where the background of the image on the left should scale vertically based on the height of the text on the right.

I tried a lot of different approaches, from GeometryReader to .layoutPriority(), but I haven't managed to get any of them to work.

Current state:

Current state

Desired state:

enter image description here

I know that I could imitate the functionality by hardcoding the .frame(100) for the example I posted, but as text on the right is dynamic, that wouldn't work.

This is full code for the view in the screenshot:

import SwiftUI

struct DynamicallyScalingView: View {
    var body: some View {
        HStack(spacing: 20) {
            Image(systemName: "snow")
                .font(.system(size: 32))
                .padding(20)
                .background(Color.red.opacity(0.4))
                .cornerRadius(8)

            VStack(alignment: .leading, spacing: 8) {
                Text("My Title")
                    .foregroundColor(.white)
                    .font(.system(size: 13))
                    .padding(5)
                    .background(Color.black)
                    .cornerRadius(8)
                Text("Dynamic text that can be of different leghts. Spanning from one to multiple lines. When it's multiple lines, the background on the left should scale vertically")
                    .font(.system(size: 13))
            }
        }
        .padding(.horizontal)
    }
}

struct DailyFactView_Previews: PreviewProvider {
    static var previews: some View {
        DynamicallyScalingView()
    }
}
Nace
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1 Answers1

10

Here is a solution based on view preference key. Tested with Xcode 11.4 / iOS 13.4

demo

struct DynamicallyScalingView: View {
    @State private var labelHeight = CGFloat.zero     // << here !!

    var body: some View {
        HStack(spacing: 20) {
            Image(systemName: "snow")
                .font(.system(size: 32))
                .padding(20)
                .frame(minHeight: labelHeight)       // << here !!
                .background(Color.red.opacity(0.4))
                .cornerRadius(8)

            VStack(alignment: .leading, spacing: 8) {
                Text("My Title")
                    .foregroundColor(.white)
                    .font(.system(size: 13))
                    .padding(5)
                    .background(Color.black)
                    .cornerRadius(8)
                Text("Dynamic text that can be of different leghts. Spanning from one to multiple lines. When it's multiple lines, the background on the left should scale vertically")
                    .font(.system(size: 13))
            }
            .background(GeometryReader {      // << set right side height
                Color.clear.preference(key: ViewHeightKey.self, 
                    value: $0.frame(in: .local).size.height) 
            })
        }
        .onPreferenceChange(ViewHeightKey.self) { // << read right side height
            self.labelHeight = $0        // << here !!
        }
        .padding(.horizontal)
    }
}

struct ViewHeightKey: PreferenceKey {
    static var defaultValue: CGFloat { 0 }
    static func reduce(value: inout Value, nextValue: () -> Value) {
        value = value + nextValue()
    }
}

backup

Asperi
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  • What is the reason to set `.frame(minHeight: labelHeight)` instead of `.frame(height: labelHeight)`? – Nace Jun 18 '20 at 19:21