# init(id:for:content:defaultValue:) Creates a data-presenting window group with an identifier and a default value. ``` nonisolated init(id: String, for type: D.Type = D.self, @ContentBuilder content: @escaping (Binding) -> C, defaultValue: @escaping () -> D) where Content == PresentedWindowContent, D : Decodable, D : Encodable, D : Hashable, C : View ``` ## Parameters `id` A string that uniquely identifies the window group. Identifiers must be unique among the window groups in your app. `type` The type of presented data this window group accepts. `content` A closure that creates the content for each instance of the group. The closure receives a binding to the value that you pass into the [`openWindow`](/documentation/SwiftUI/EnvironmentValues/openWindow) action when you open the window. SwiftUI automatically persists and restores the value of this binding as part of the state restoration process. `defaultValue` A closure that returns a default value to present. SwiftUI calls this closure when it has no data to provide, like when someone opens a new window from the File > New Window menu item. ## Discussion The window group uses the given view as a template to form the content of each window in the group. SwiftUI creates a window from the group when you present a value of the specified type using the [`openWindow`](/documentation/SwiftUI/EnvironmentValues/openWindow) action. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)