EnvironmentKey

public protocol EnvironmentKey

Types conforming to this protocol can be used as keys in an Environment.

Using a type as the key allows us to strongly type each value, with the key’s EnvironmentKey.Value associated value.

Example

Usually a key is implemented with an uninhabited type, such an empty enum.

enum WidgetCountKey: EnvironmentKey {
    static let defaultValue: Int = 0
}

You can write a small extension on Environment to make it easier to use your key.

extension Environment {
    var widgetCount: Int {
        get { self[WidgetCountKey.self] }
        set { self[WidgetCountKey.self] = newValue }
    }
}