iOS 14 has Changed (or broken?) SwiftUI GeometryReader

Question

As of today's release of iOS 14.0 my iOS code, which depends heavily on GeometryReader for layout, is no longer working well. I.e, layout has been kind of randomized.

In the Xcode debugger I have compared the same code running on iOS 13.6 vs iOS 14.0 and see that the problem is that the GeometryProxy structure is not being initialized in iOS 14.0.

In the example code below the variable g, a GeometryProxy, has valid width and height values in iOS 13 but is all zero's in iOS 14. (This is just one of the simpler uses I make of GeometryProxy values -- I would appreciate if nobody points out the obvious fact that this snippet could be accomplished much more easily in another way.)

Is this a change to the GeometryReader or a bug? Anyone have a workaround? Did I make a huge mistake depending on GeometryReader for dynamic layout?

struct TextView: View {
  @EnvironmentObject var data: RecorderData
  let m = MusicalNote()

  var body: some View {
      GeometryReader { g in
          Stack(alignment: .leading) {
              Text(self.data.curNote.getString())
                 .font(.system(size: g.size.height / 2.4))
                 .padding(.bottom)
              Text(self.data.fdata.fingerings[self.data.curRecorder.id] ![self.data.curNote.seq] ![self.data.curFingType] ![self.data.currentFingeringChoice].comment)
                 .font(.headline)
        }
      Spacer()
    }
  }
}

Answer 1

It's definitely changed - this post sums it up: https://swiftui-lab.com/geometryreader-bug/

GeometryReader now lays out its content different to how it used to. It used to centre it horizontally and vertically in the parent but now it aligns it to the top-left.

My app looks awful - what's frustrating is it's not clear if this is new behaviour and is as-designed, or whether it's a bug and will be fixed. I'm trying to go through my app and manually apply offsets but the dynamic nature of layouts using GeometryReader means it is not always easy.

Answer 2

Editing my previous answer as its now obviously bad advice

From https://developer.apple.com/documentation/xcode-release-notes/xcode-12-release-notes

Rebuilding against the iOS 14, macOS 11, watchOS 7, and tvOS 14 SDKs changes uses of GeometryReader to reliably top-leading align the views inside the GeometryReader. This was the previous behavior, except when it wasn’t possible to detect a single static view inside the GeometryReader. (59722992) (FB7597816)

Which says, to me at least, that the previous behaviour was buggy by their standards - despite it matching the conventions for other layout containers like VStack. And that this behaviour is the new normal.