Pushes a single value back for a specific attribute.


func SecTransformPushbackAttribute(_ ref: SecTransformImplementationRef, _ attribute: SecTransformStringOrAttribute, _ value: CFTypeRef) -> CFTypeRef?



A SecTransformImplementationRef that is bound to an instance of a custom transform.


The name or the attribute handle of the attribute whose value is to be pushed back. When using a name, see Transform Attributes for a list of valid key names.


The value being pushed back.

Return Value

An error on failure, or nil on success.


Calling this function stops the flow of data into the specified attribute until any attribute is changed for the transform instance bound to the ref parameter.

See Also

Transform Characteristics

func SecTransformGetAttribute(SecTransform, CFString) -> CFTypeRef?

Gets the current value of a transform attribute.

Transform Attributes

Specify the attributes of a transform.

typealias SecTransformAttribute

A direct reference to a security transform attribute.

typealias SecTransformStringOrAttribute

A type that may be either a string or an attribute reference.

enum SecTransformMetaAttributeType

The keys that describe the metadata attributes of transform attributes.