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NSControllerPlaceholders

Overview

The NSControllerPlaceholders class provides an means for an object to register default placeholders that will be displayed for a binding when no other placeholder has been specified. Individual placeholder values can be specified for each of the marker objects, as well as when the property is null.

Placeholders are used when a property of an instance of the receiving class is accessed through a key value coding compliant method, and returns null or a specialized marker.

Tasks

Constructors

• NSControllerPlaceholders

Managing Default Placeholders

• setDefaultPlaceholderForMarker
• defaultPlaceholderForMarker

Obtaining Controller Markers

• multipleValuesMarker
• noSelectionMarker
• notApplicableMarker

Testing Markers

• isControllerMarker

Static Methods

defaultPlaceholderForMarker

Returns an object that will be used as the placeholder for the binding, when a key value coding compliant property of an instance of classObject returns the value specified by marker, and no other placeholder has been specified.

public static Object defaultPlaceholderForMarker(Class classObject, Object marker, String binding)

Discussion

marker can be null or one of the controller markers returned by multipleValuesMarker, noSelectionMarker, and notApplicableMarker.

Availability

• Available in Mac OS X v10.3 and later.

See Also

• setDefaultPlaceholderForMarker

isControllerMarker

Returns whether marker is a valid controller marker.

public static boolean isControllerMarker(Object marker)

Discussion

Valid controller markers are returned by multipleValuesMarker, noSelectionMarker, and notApplicableMarker.

Availability

• Available in Mac OS X v10.3 and later.

multipleValuesMarker

Returns a marker which indicates that a controller’s selection contains multiple items.

public static Object multipleValuesMarker()

Availability

• Available in Mac OS X v10.3 and later.

See Also

• noSelectionMarker
• notApplicableMarker

noSelectionMarker

Returns a marker which indicates that a controller’s selection is currently empty.

public static Object noSelectionMarker()

Availability

• Available in Mac OS X v10.3 and later.

See Also

• multipleValuesMarker
• notApplicableMarker

notApplicableMarker

Returns a marker which indicates that a controller does not support selection.

public static Object notApplicableMarker()

Discussion

NSUserDefaultsController is an example of a controller that does not support the concept of selection.

Availability

• Available in Mac OS X v10.3 and later.

See Also

• multipleValuesMarker
• noSelectionMarker

setDefaultPlaceholderForMarker

Sets placeholder as the default placeholder for the binding, when a key value coding compliant property of an instance of classObject returns the value specified by marker, and no other placeholder has been specified.

public static void setDefaultPlaceholderForMarker(Class classObject, Object placeholder, Object marker, String binding)

Discussion

marker can be null or one of the controller markers returned by multipleValuesMarker, noSelectionMarker, and notApplicableMarker.

Availability

• Available in Mac OS X v10.3 and later.

See Also

• defaultPlaceholderForMarker

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