The CFNull opaque type defines a unique object used to represent null values in collection objects (which don’t allow NULL values). CFNull objects are neither created nor destroyed. Instead, a single CFNull constant object—kCFNull—is defined and is used wherever a null value is needed.

The CFNull opaque type is available in macOS 10.2 and later.


CFNull Miscellaneous Functions

func CFNullGetTypeID() -> CFTypeID

Returns the type identifier for the CFNull opaque type.

Data Types

class CFNull

A reference to a CFNull object.


Predefined Value

Predefined CFNull object.

See Also

Opaque Types


The CFFileDescriptor provides an opaque type to monitor file descriptors for read and write activity via CFRunLoop.


CFStringTokenizer allows you to tokenize strings into words, sentences or paragraphs in a language-neutral way. It supports languages such as Japanese and Chinese that do not delimit words by spaces, as well as de-compounding German compounds. You can obtain Latin transcription for tokens. It also provides language identification API.