---
title: nullDevice
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/filehandle/nulldevice
---

# nullDevice

The file handle associated with a null device.

## Declaration

```swift
class var nullDevice: FileHandle { get }
```

## Return Value

Return Value A file handle associated with a null device.

## Discussion

Discussion You can use null-device file handles as “placeholders” for standard-device file handles or in collection objects to avoid exceptions and other errors resulting from messages being sent to invalid file handles. Read messages sent to a null-device file handle return an end-of-file indicator (an empty NSData object) rather than raise an exception. Write messages are no-ops, whereas fileDescriptor returns an illegal value. Other methods are no-ops or return “sensible” values. When using this method to create a file handle object, the file handle owns its associated file descriptor and is responsible for closing it.

## See Also

### Related Documentation

- [init(fileDescriptor:)](foundation/filehandle/init(filedescriptor:).md)

### Getting a file handle

- [standardError](foundation/filehandle/standarderror.md)
- [standardInput](foundation/filehandle/standardinput.md)
- [standardOutput](foundation/filehandle/standardoutput.md)