NSExpressionDescription
| Inherits from | |
| Conforms to | |
| Framework | /System/Library/Frameworks/CoreData.framework |
| Availability | Available in Mac OS X v10.6 and later. |
| Companion guide | |
| Declared in | NSExpressionDescription.h |
Overview
Instances of NSExpressionDescription objects represent a special property description type intended for use with the NSFetchRequest propertiesToFetch method.
An NSExpressionDescription describes a column to be returned from a fetch that may not appear directly as an attribute or relationship on an entity. Examples might include upper(attribute) or max(attribute). You cannot set an NSExpressionDescription object as a property of an entity.
Instance Methods
expression
Returns the expression for the receiver.
- (NSExpression *)expression
Return Value
The expression for the receiver.
Availability
- Available in Mac OS X v10.6 and later.
See Also
Declared In
NSExpressionDescription.hexpressionResultType
Returns the type of the receiver.
- (NSAttributeType)expressionResultType
Return Value
The type of the receiver.
Availability
- Available in Mac OS X v10.6 and later.
See Also
Declared In
NSExpressionDescription.hsetExpression:
Sets the expression for the receiver.
- (void)setExpression:(NSExpression *)expression
Parameters
- expression
The expression for the receiver.
Special Considerations
This method raises an exception if the receiverâs model has been used by an object graph manager.
Availability
- Available in Mac OS X v10.6 and later.
See Also
Declared In
NSExpressionDescription.hsetExpressionResultType:
Sets the type of the receiver.
- (void)setExpressionResultType:(NSAttributeType)type
Parameters
- type
An
NSAttributeTypeconstant that specifies the type for the receiver.
Special Considerations
This method raises an exception if the receiverâs model has been used by an object graph manager.
Availability
- Available in Mac OS X v10.6 and later.
See Also
Declared In
NSExpressionDescription.h© 2009 Apple Inc. All Rights Reserved. (Last updated: 2009-02-03)
