KeyWindow

This package provides a way to share values from the key window to all other parts of your application. (the key window in macOS/iPadOS is the window that currently responds to keyboard shortcuts).

The main use-case of this package is to make it possible to pass values from the key window to the commands section in a swiftUI lifecycle application.

import KeyWindow

@main
struct ExampleWindowReaderApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView().observeWindow()
        }.commands {
            CommandMenu("MyMenue") {
                MenuButton()
            }
        }
    }
}

Within our ContentView and its children we can publish values in a similar way to publishing Preferences.

First create a struct that conforms to KeyWindowValueKey and declare the value type.

struct SelectedProjectWindowValueKey: KeyWindowValueKey {
    typealias Value = Binding<UUID>
}

struct SelectedProjectTitleWindowValueKey: KeyWindowValueKey {
    typealias Value = String
}

Then to provide these within our views we can set these using .keyWindow(SelectedProjectWindowValueKey.self, $projectSelection). This will bubble up and when the window becomes key then we can read these values within our MenuButton.

struct MenuButton: View {
    @KeyWindowValue(SelectedProjectTitleWindowValueKey.self)
    var title: String
    
    @KeyWindowValueBinding(SelectedProjectWindowValueKey.self)
    var selectedProject: UUID?

    var body: some View {
        Button(action: {
            // Delete the selectedProject
            self.selectedProject = // some other project
        }, label: {
            Text("Delete \(title)")
        })
    }
}

You can can also use @KeyWindowValue and @KeyWindowValueBinding in your other views but be careful to ensure they do not result in .keyWindow modifiers being re-called otherwise it is possible to get into a loop. The best way to do this is to set all your .keyWindow high up in your view structor and only use @KeyWindowValue and @KeyWindowValueBinding on deeply nested child views.

In addition this package also provides a EnvironmentValues.isKeyWindow that can be read to detect if the view is in the key window. (you might use this to change the style of rendering). Note this is not the same as scenePhase, scenePhase indicates if the scene is active not if the window for the view is in the Key Window. On iPadOS and macOS you can have multiple scenes active and on macOS each Scene can have many windows but only one of them will be key at any given time.

If you have a Binding<Optional<Value>> that that you want to share through the .keyWindow you can do this by using the @KeyWindowOptionalValueBinding wrapper.

renarl/KeyWindow

KeyWindow