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# callAsFunction(id:)

Opens a window that’s associated with the specified identifier.

```
@MainActor @preconcurrency func callAsFunction(id: String)
```

## Parameters

`id`

The identifier of the scene to present.

## Discussion

Don’t call this method directly. SwiftUI calls it when you
call the [`openWindow`](/documentation/SwiftUI/EnvironmentValues/openWindow) action with an identifier:

```
openWindow(id: "message")
```

For information about how Swift uses the `callAsFunction()` method to
simplify call site syntax, see
[Methods with Special Names](https://docs.swift.org/swift-book/ReferenceManual/Declarations.html#ID622)
in *The Swift Programming Language*.

---

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