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How to create and use custom environment values

Paul Hudson @twostraws June 21st 2024

Updated for Xcode 16.4

Improved in iOS 18

SwiftUI's @Entry macro makes it straightforward to create custom values for the environment, although I'd recommend you also add a View extension to make your code clearer.

The first step is to make an extension on EnvironmentValues, using @Entry inside there to create your custom environment key, give it a type, and also give it a default value:

extension EnvironmentValues {
    @Entry var iconColor: Color = .red
}

The @Entry macro automatically turns that into a fully fledged environment key and value, meaning that we can now use environment(\.iconColor, .blue) to set a value, and @Environment(\.iconColor) to read that value back out, like this:

struct BubblesView: View {
    @Environment(\.iconColor) var iconColor

    var body: some View {
        Image(systemName: "bubbles.and.sparkles.fill")
            .foregroundStyle(iconColor)
            .font(.largeTitle)
    }
}

struct ContentView: View {
    var body: some View {
        HStack {
            BubblesView()
                .environment(\.iconColor, .blue)

            BubblesView()
                .environment(\.iconColor, .red)
        }
    }
}

How to create and use custom environment values

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