What is the recommended way to convert between pixels and points in SwiftUI?

Question

I want to display a QR code in SwiftUI. The code is generated as a CGImage via CIImage. I don't want to scale it to the full size available because if the scaling factor isn't an integer there may be fuzzy boundaries between the QR modules. So I need a way to convert between iOS display points which I can get with GeometryReader and physical points. I've found a few search "hits" about reading the screen scale from a UIView, but not how I can get this scale in SwiftUI.

There a few more hits which just say the scale is 3 on all modern iPhones, and as I'm targeting iOS 15+ I think I can safely assume it's always 3 for now, but what if Apple bring out even higher pixel densities in future?

Answer 1

You can get displayScale using the Environment property wrapper.

struct ContentView: View {
    @Environment(\.displayScale) var displayScale

    var body: some View {
        Text("display scale: \(displayScale)")
    }
}

Consult EnvironmentValues to see what else SwiftUI provides in the “environment”.