---
title: "CFShow(_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfshow(_:)"
---

# CFShow(_:)

Prints a description of a Core Foundation object to stderr.

## Declaration

```swift
func CFShow(_ obj: CFTypeRef!)
```

## Parameters

- `obj`: A Core Foundation object derived from CFType. If obj is not a Core Foundation object, an assertion is raised.

## Discussion

Discussion The output is printed to the standard I/O standard error (stderr). This function is useful as a debugging aid for Core Foundation objects. Because these objects are based on opaque types, it is difficult to examine their contents directly. However, the opaque types implement description function callbacks that return descriptions of their objects. This function invokes these callbacks. Special Considerations You can use CFShow in one of two general ways. If your debugger supports function calls (such as gdb does), call CFShow in the debugger: (gdb) call (void) CFShow(string) Hello World You can also incorporate calls to CFShow in a test version of your code to print out “snapshots” of Core Foundation objects to the console.

## See Also

### Miscellaneous Functions

- [CFCopyDescription(_:)](corefoundation/cfcopydescription(_:).md)
- [CFCopyTypeIDDescription(_:)](corefoundation/cfcopytypeiddescription(_:).md)
- [CFGetTypeID(_:)](corefoundation/cfgettypeid(_:).md)