EnvironmentValuesが大域変数ではないことを示すサンプルコード

EnvironmentValuesSample1.swift

import SwiftUI

extension EnvironmentValues {
    @Entry var myColor = Color.blue
}

struct ScreenX: View {
    @Environment(\.myColor) var myColor: Color

    var body: some View {
        HStack {
            ScreenY()
            ScreenY().environment(\.myColor, .orange)
        }
        .padding()
        .background(myColor)
        .scaledToFit()
        .border(.red, width: 2)
    }
}

struct ScreenY: View {
    @Environment(\.myColor) var myColor: Color

    var body: some View {
        HStack {
            ScreenZ()
            ScreenZ().environment(\.myColor, .green)
        }
        .padding()
        .background(myColor)
        .scaledToFit()
        .border(.red, width: 2)
    }
}

struct ScreenZ: View {
    @Environment(\.myColor) var myColor: Color

    var body: some View {
        myColor
            .scaledToFit()
            .border(.red, width: 2)
    }
}

#Preview {
    ScreenX()
}