Issue #821

Suppose we have a 16:9 preview Image and we want the title Text to be the same width

First we need PreferenceKey to store and sync size

struct SizePreferenceKey: PreferenceKey {
    typealias Value = CGSize
    static var defaultValue: Value = .zero

    static func reduce(value: inout Value, nextValue: () -> Value) {
        value = nextValue()

For our Image, we use a GeometryReader in the background with invisible View Color.clear to get its size, then sync to our preference key.

@State private var previewImageSize: CGSize = .zero

Image(uiImage: image)
    .aspectRatio(16/9, contentMode: .fit)
    .frame(height: 180)
        GeometryReader { geo in
                    key: SizePreferenceKey.self,
                    value: geo.size
    .onPreferenceChange(SizePreferenceKey.self) { preferences in
        self.previewImageSize = preferences
Screenshot 2021-07-06 at 07 29 29

Then in our Text, we set frame with maxWidth based on the previewImageSize State

VStack(alignment: .leading {
.frame(maxWidth: previewImageSize.width, alignment: .leading)

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