Enterprise Objects Framework Release 1.0 Copyright ©1994 by NeXT Computer, Inc.  All Rights Reserved.

NSValue

	Inherits From:	NSObject
	Conforms To:	NSCopying NSMutableCopying
	Declared In:	foundation/NSValue.h

Class Description

NSValue objects provides an object-oriented wrapper for the data types defined in standard C and Objective C. The NSValue class declares the programmatic interface to an object that contains a C data type. It provides methods for creating value objects that contain values of a specified data type, pointers, and other objects. The NSValue class is often used to put Objective C and standard C data types into collections that require objects, such as NSArrays. When a value object is instantiated, it is encoded with the specified data type.

Instance Variables

None declared in this class.

Adopted Protocols

NSCopying

copy

copyWithZone:

NSMutableCopying

mutableCopy

mutableCopyWithZone:

Method Types

Allocating and initializing

+ value:withObjCType:

+ valueWithNonretainedObject: + valueWithPointer:

Accessing data

getValue

nonretainedObjectValue objCType pointerValue

Class Methods

value:withObjCType:

+ (NSValue *)value:(const void*)value withObjCType:(const char *)type

Creates and returns a value object containing value of the Objective C type type in the specified zone. This excerpt creates and initializes a value object valObj and encodes its data to be of the type NSRange.

NSRange myRange = {4, 10};
NSValue *valObj = [NSValue value:&myRange
withObjCType:@encode(NSRange)];

valueWithNonretainedObject:

+ (NSValue *)valueWithNonretainedObject:anObject

Creates and returns a value object containing the object anObject without retaining anObject. The statement [NSValue valueWithNonretainedOject:obj] is equivalent to the statement [NSValue value:&obj withObjCType:@encode(void *)].

valueWithPointer:

+ (NSValue *)valueWithPointer:(void *)pointer

Creates and returns a value object that contains a pointer. The statement [NSValue valueWithPointer:pointer] is equivalent to the statement [NSValue value:&pointer withObjCType:@encode(void *)]. See also:  data (NSData)

Instance Methods

getValue:

(void)getValue:(void *)value

Copies the data in a value object into the caller's variable value. This excerpt creates a value object valObj and then uses getValue: to copy a pointer to valObj's data into valPtr.

NSValue* valObj;
int theInt = 123;
const void *myVal = &theInt;
void *valPtr;
valObj = [NSValue
value:myVal
withObjCType:@encode(int*)];
[valObj getValue:&valPtr];

See also:  bytes (NSData), getBytes:length: (NSData), getBytes:range: (NSData) nonretainedObjectValue

nonretainedObjectValue

Returns a non-retained object from a value object. See also:  bytes (NSData), getBytes:length: (NSData), getBytes:range: (NSData) objCType

(const char *)objCType

Returns the Objective C type of the data contained in a value object. This excerpt assigns to type a const char* representation of the Objective C type for the data contained in valObj.

const char* type;
NSValue* valObj;
...
type = [valObj objCType];

See also:  bytes (NSData), getBytes:length: (NSData), getBytes:range: (NSData) pointerValue

(void *)pointerValue

Returns the value pointed to by a pointer contained in an value object. See also:  initWithBytesNoCopy:length: (NSData)