---
title: "panel(_:validate:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsopensavepaneldelegate/panel(_:validate:)"
---

# panel(_:validate:)

Asks the delegate to validate the URL for a file that the user selected.

## Declaration

```swift
@MainActor optional func panel(_ sender: Any, validate url: URL) throws
```

## Parameters

- `sender`: The panel that requests URL validation.
- `url`: The URL for you to validate.

## Discussion

Discussion Save panels call this method when the user clicks the Save button. Open panels call it when the user clicks the Open button. An Open panel calls this method once for each selected filename or directory. note: In Swift, this method returns Void and is marked with the throws keyword to indicate that it throws an error in cases of failure. You call this method in a try expression and handle any errors in the catch clauses of a do statement, as described in Error Handling in The Swift Programming Language and About Imported Cocoa Error Parameters.

## See Also

### Validating the Panel Content

- [panel(_:shouldEnable:)](appkit/nsopensavepaneldelegate/panel(_:shouldenable:).md)