---
title: fileModificationDate
framework: appkit
role: symbol
role_heading: Instance Property
path: appkit/nsdocument/filemodificationdate
---

# fileModificationDate

The last-known modification date of the document’s on-disk representation.

## Declaration

```swift
nonisolated var fileModificationDate: Date? { get set }
```

## Discussion

Discussion The NSDocument default file saving machinery uses this information to warn the user when the on-disk representation of an open document has been modified by something other than the current app.

## See Also

### Getting Document Metadata

- [fileURL](appkit/nsdocument/fileurl.md)
- [isEntireFileLoaded](appkit/nsdocument/isentirefileloaded.md)
- [keepBackupFile](appkit/nsdocument/keepbackupfile.md)
- [isDraft](appkit/nsdocument/isdraft.md)
- [fileType](appkit/nsdocument/filetype.md)
- [isDocumentEdited](appkit/nsdocument/isdocumentedited.md)
- [isInViewingMode](appkit/nsdocument/isinviewingmode.md)