---
title: "callAsFunction(_:completion:)"
framework: swiftui
role: symbol
role_heading: Instance Method
path: "swiftui/openurlaction/callasfunction(_:completion:)"
---

# callAsFunction(_:completion:)

Asynchronously opens a URL, following system conventions.

## Declaration

```swift
@MainActor @preconcurrency func callAsFunction(_ url: URL, completion: @escaping (Bool) -> Void)
```

## Parameters

- `url`: The URL to open.
- `completion`: A closure the method calls after determining if it can open the URL, but possibly before fully opening the URL. The closure takes a Boolean value that indicates whether the method can open the URL.

## Discussion

Discussion Don’t call this method directly. SwiftUI calls it when you call the OpenURLAction structure that you get from the Environment, using a URL and a completion handler as arguments: struct OpenURLExample: View {     @Environment(\.openURL) private var openURL

var body: some View {         Button {             if let url = URL(string: "https://www.example.com") {                 // Implicitly calls openURL.callAsFunction(url) { ... }                 openURL(url) { accepted in                     print(accepted ? "Success" : "Failure")                 }             }         } label: {             Label("Get Help", systemImage: "person.fill.questionmark")         }     } } For information about how Swift uses the callAsFunction() method to simplify call site syntax, see Methods with Special Names in The Swift Programming Language.

## See Also

### Calling the action

- [callAsFunction(_:)](swiftui/openurlaction/callasfunction(_:).md)