EOKeyValueCodingAdditions
(informal protocol)
Declared in:
- EOControl/EOKeyValueCoding.h
Protocol Description
The EOKeyValueCodingAdditions informal protocol defines extensions to the basic EOKeyValueCoding informal protocol. One pair of methods, takeValuesFromDictionary: and valuesForKeys:, gives access to groups of properties. Another pair of methods, takeValue:forKeyPath: and valueForKeyPath: give access to properties across relationships with key paths of the form relationship.property; for example, "department.name". the Framework additions to NSObject provide default implementations of EOKeyValueCodingAdditions, which you rarely (if ever) need to override.
EONull in Collections
Because collection objects such as NSArray and NSDictionary
can't contain nil as a value, nil must be represented by a special
object, EONull. EONull provides a single instance that represents
the NULL value for object attributes. The default implementations
of takeValuesFromDictionary: and valuesForKeys: translate EONull
and nil
between NSDictionaries
and enterprise objects so your objects don't have to explicitly
test for EONull values.
Instance Methods
takeValue:forKeyPath:
- (void)takeValue:(id)value
forKeyPath:(NSString *)keyPath
takeValuesFromDictionary:
- (void)takeValuesFromDictionary:(NSDictionary
*)aDictionary
valueForKeyPath:
- (id)valueForKeyPath:(NSString
*)keyPath
valuesForKeys:
- (NSDictionary *)valuesForKeys:(NSArray
*)keys