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Authors
- Richard Frith-Macdonald (
rfm@gnu.org
)
-
Date: Generated at 2024-11-18 21:56:13 +0100
Copyright: (C) 2000,2002 Free Software Foundation, Inc.
- Declared in:
- Foundation/NSKeyValueCoding.h
Availability: MacOS-X 10.0.0
This describes an informal protocol for
key-value coding, a mechanism whereby the
fields of an object may be accessed and set using
generic methods in conjunction with string keys
rather than field-specific methods. Key-based access
loses compile-time validity checking, but can be
convenient in certain kinds of situations.
The basic methods are implemented as a category of the
NSObject
class, but other classes override those default
implementations to perform more specific
operations.
+ (BOOL)
accessInstanceVariablesDirectly;
Availability: MacOS-X 10.0.0
Controls whether the NSKeyValueCoding methods may
attempt to access instance variables directly.
NSObject's implementation returns
YES
.
+ (BOOL)
useStoredAccessor;
Availability: MacOS-X 10.0.0
- (
NSDictionary*)
dictionaryWithValuesForKeys: (
NSArray*)keys;
Availability: MacOS-X 10.0.0
Returns a dictionary built from values obtained for
the specified
keys.
By default this
is derived by calling
-valueForKey:
for each key. Any
nil
values obtained are
represented by an
NSNull
instance.
- (id)
handleQueryWithUnboundKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
- (void)
handleTakeValue: (id)anObject
forUnboundKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
- (
NSMutableArray*)
mutableArrayValueForKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns a mutable array value for a given key. This
method:
-
Searches the receiver for methods matching the
patterns insertObject:in<Key>AtIndex:
and removeObjectFrom<Key>AtIndex:. If both
methods are found, each message sent to the
proxy array will result in the invocation of one
or more of these methods. If
replaceObjectIn<Key>AtIndex:withObject:
is also found in the receiver it will be used when
appropriate for better performance.
-
If the set of methods is not found, searches the
receiver for a the method set<Key>:.
Each message sent to the proxy array will result
in the invocation of set<Key>:
-
If the previous do not match, and
accessInstanceVariablesDirectly
returns
YES
, searches for an
instance variable matching _<key> or
<key> (in that order). If the
instance variable is found, messages sent to
the proxy object will be forwarded to the instance
variable.
-
If none of the previous are found, raises an
NSUndefinedKeyException
- (
NSMutableArray*)
mutableArrayValueForKeyPath: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns a mutable array value for the given key
path.
- (
NSMutableSet*)
mutableSetValueForKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns a mutable set value for a given key. This
method:
-
Searches the receiver for methods matching the
patterns add<Key>Object:,
remove<Key>Object:,
add<Key>:, and
remove<Key>:, which
correspond to the NSMutableSet methods
addObject:, removeObject:, unionSet:, and
minusSet:, respectively. If at least one
addition and one removal method are found,
each message sent to the proxy set will result in
the invocation of one or more of these methods. If
intersect<Key>: or
set<Key>: is also found in the
receiver, the method(s) will be used when
appropriate for better performance.
-
If the set of methods is not found, searches the
receiver for a the method set<Key>:.
Each message sent to the proxy set will result in
the invocation of set<Key>:
-
If the previous do not match, and
accessInstanceVariablesDirectly
returns
YES
, searches for an
instance variable matching _<key> or
<key> (in that order). If the
instance variable is found, messages sent to
the proxy object will be forwarded to the instance
variable.
-
If none of the previous are found, raises an
NSUndefinedKeyException
- (
NSMutableSet*)
mutableSetValueForKeyPath: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns a mutable set value for the given key path.
- (void)
setNilValueForKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
This method is invoked by the NSKeyValueCoding
mechanism when an attempt is made to set an null
value for a scalar attribute. This implementation
raises an NSInvalidArgument exception. Subclasses my
override this method to do custom handling. (E.g.
setting the value to the equivalent of 0.)
- (void)
setValue: (id)anObject
forKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Sets the value if the attribute associated with the
key in the receiver. The object is converted to a
scalar attribute where applicable (and
-setNilValueForKey:
is called if a
nil
value is supplied).
Tries to use a standard accessor of the form setKey:
where 'Key' is the supplied argument with the first
letter converted to uppercase.
If the
receiver's class allows
+accessInstanceVariablesDirectly
it continues with instance variables:
Invokes
-setValue:forUndefinedKey:
if no accessor mechanism can be found and raises
NSInvalidArgumentException if
the accessor method doesn't take exactly one argument
or the type is unsupported (e.g. structs). If the
receiver expects a scalar value and the value
supplied is the NSNull instance or
nil
, this method invokes
-setNilValueForKey:
.
- (void)
setValue: (id)anObject
forKeyPath: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Retrieves the object returned by invoking
-valueForKey:
on the receiver with the first key component supplied by
the key path. Then invokes
-setValue:forKeyPath:
recursively on the returned object with rest of
the key path. The key components are delimited by '.'.
If the key path doesn't contain any '.', this method
simply invokes
-setValue:forKey:
.
- (void)
setValue: (id)anObject
forUndefinedKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Invoked when
-setValue:forKey:
/
-takeStoredValue:forKey:
are called with a key which can't be associated with an
accessor method or instance variable. Subclasses
may override this method to add custom handling.
NSObject raises an NSUndefinedKeyException, with a
userInfo dictionary containing
NSTargetObjectUserInfoKey with
the receiver an NSUnknownUserInfoKey with the supplied
key entries.
Called when the key passed to
-setValue:forKey:
cannot be used.
- (void)
setValuesForKeysWithDictionary: (
NSDictionary*)aDictionary;
Availability: MacOS-X 10.0.0
- (id)
storedValueForKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns the value associated with the supplied key
as an object. Scalar attributes are converted to
corresponding objects. Uses private accessors
in favor of the public ones, if the receiver's class
allows
+useStoredAccessor
. Otherwise this method invokes
-valueForKey:
. The search order is:
Private accessor methods:
If the receiver's class allows
+accessInstanceVariablesDirectly
it continues with instance variables:
Public accessor methods:
Invokes
-handleTakeValue:forUnboundKey:
if no accessor mechanism can be found and raises
NSInvalidArgumentException if
the accessor method takes takes any arguments or the
type is unsupported (e.g. structs).
- (void)
takeStoredValue: (id)anObject
forKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Sets the value associated with the supplied in the
receiver. The object is converted to the scalar
attribute where applicable. Uses the private
accessors in favor of the public ones, if the
receiver's class allows
+useStoredAccessor
. Otherwise this method invokes
-takeValue:forKey:
. The search order is:
Private accessor methods:
If the receiver's
class allows accessInstanceVariablesDirectly it
continues with instance variables:
Public accessor methods:
Invokes
-handleTakeValue:forUnboundKey:
if no accessor mechanism can be found and raises
NSInvalidArgumentException if
the accessor method doesn't take exactly one argument
or the type is unsupported (e.g. structs). If the
receiver expects a scalar value and the value
supplied is the NSNull instance or
nil
, this method invokes
-unableToSetNilForKey:
.
- (void)
takeStoredValuesFromDictionary: (
NSDictionary*)aDictionary;
Availability: MacOS-X 10.0.0
Iterates over the dictionary invoking
-takeStoredValue:forKey:
on the receiver for each key-value pair, converting
NSNull to
nil
.
- (void)
takeValue: (id)anObject
forKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Sets the value if the attribute associated with the
key in the receiver. The object is converted to a
scalar attribute where applicable. Uses the public
accessors in favor of the private ones. The
search order is:
Accessor methods:
If the receiver's class allows
+accessInstanceVariablesDirectly
it continues with instance variables:
Invokes
-handleTakeValue:forUnboundKey:
if no accessor mechanism can be found and raises
NSInvalidArgumentException if
the accessor method doesn't take exactly one argument
or the type is unsupported (e.g. structs). If the
receiver expects a scalar value and the value
supplied is the NSNull instance or
nil
, this method invokes
-unableToSetNilForKey:
.
Deprecated... use
-setValue:forKey:
instead.
- (void)
takeValue: (id)anObject
forKeyPath: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Retrieves the object returned by invoking
-valueForKey:
on the receiver with the first key component supplied by
the key path. Then invokes
-takeValue:forKeyPath:
recursively on the returned object with rest of
the key path. The key components are delimited by '.'.
If the key path doesn't contain any '.', this method
simply invokes
-takeValue:forKey:
.
Deprecated... use
-setValue:forKeyPath:
instead.
- (void)
takeValuesFromDictionary: (
NSDictionary*)aDictionary;
Availability: MacOS-X 10.0.0
- (void)
unableToSetNilForKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
- (BOOL)
validateValue: (id*)aValue
forKey: (
NSString*)aKey
error: (out
NSError**)anError;
Availability: MacOS-X 10.0.0
Returns a boolean indicating whether the object
pointed to by aValue is valid for
setting as an attribute of the receiver using the
name aKey. On success (YES
response) it may return a new value to be used in
aValue. On failure (NO
response) it may return an error in
anError.
The method works by
calling a method of the receiver whose name is of
the form validateKey:error: if the receiver has
implemented such a method, otherwise it simply
returns YES
.
- (BOOL)
validateValue: (id*)aValue
forKeyPath: (
NSString*)aKey
error: (out
NSError**)anError;
Availability: MacOS-X 10.0.0
- (id)
valueForKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns the value associated with the supplied key
as an object. Scalar attributes are converted to
corresponding objects.
The search
order is:
Accessor methods:
If
the receiver's class allows
+accessInstanceVariablesDirectly
it continues with private accessors:
and then instance variables:
Invokes
-setValue:forUndefinedKey:
if no accessor mechanism can be found and raises
NSInvalidArgumentException if
the accessor method takes any arguments or the type is
unsupported (e.g. structs).
- (id)
valueForKeyPath: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Returns the object returned by invoking
-valueForKeyPath:
recursively on the object returned by invoking
-valueForKey:
on the receiver with the first key component supplied by
the key path. The key components are delimited by '.'.
If the key path doesn't contain any '.', this method
simply invokes
-valueForKey:
.
- (id)
valueForUndefinedKey: (
NSString*)aKey;
Availability: MacOS-X 10.0.0
Invoked when
-valueForKey:
/
-storedValueForKey:
are called with a key, which can't be associated with
an accessor method or instance variable. Subclasses may
override this method to add custom handling.
NSObject raises an NSUndefinedKeyException, with a
userInfo dictionary containing
NSTargetObjectUserInfoKey with
the receiver an NSUnknownUserInfoKey with the supplied
key entries.
- (
NSDictionary*)
valuesForKeys: (
NSArray*)keys;
Availability: MacOS-X 10.0.0
Iterates over the array sending the receiver
-valueForKey:
for each object in the array and inserting the result
in a dictionary. All
nil
values returned by
-valueForKey:
are replaced by the NSNull instance in the dictionary.
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