GNU Free Documentation License . .

Objective-C

( «Objective C»)
: ,
Objective-C
:

-, : -
:

1986
():

:

, /

:

Cocoa, gcc, LLVM + Clang
:

Smalltalk, C
:

Java, Objective-J
:

apple.com, Objective-C

Objective-C, Objective C, ObjC Obj-C  - Apple, Smalltalk.

C++, Objective-C ( Objective-C ) . Smalltalk, .

Objective-C GCC . Mac OS X (Cocoa) GNUstep  - OpenStep. iOS (Cocoa Touch).

[]

1980- . «» , . , , . , .

- . , Smalltalk - .   .

ObjC 1980 Stepstone. .

, software IC. (), .

, .

, , .

Objective-C   - .[?]   - . Objective-C.

Objective-C   , , .

, message-oriented C++  function-oriented. , ( ), ( ) , , Smalltalk-.

  , . ( ), ( , ).

.

Objective-C   , ( ) instance-, ,  . .

( ). ( ), . ( , ).

Objective-C gcc llvm ( Windows MinGW cygwin).

runtime- . gcc . runtime- Apple: Apples Objective-C runtime.

runtime- ( ), runtime- Apple.

[]

Objective-C id. id . nil (= NULL).

id .   , .

, ( , ).

:

   [receiver message];

receiver , message  .

C++ nil , (nil).

:

   [myRect setOrigin:30.0 :50.0];

() setOrigin::. , . ( ),   .

Objective-C , .

   [myRect setWidth:10.0 height:20.0];

setWidth: height:.

:

   [myObject makeGroup: obj1, obj2, obj3, obj4, nil];

, , , , , id.

   float area = [myRect area];

:

   [myRect setColor:[otherRect color]];

, Objective-C . ( class objects) ( Abstract Factory).

  ( ). , ( receiver).

   Rect * myRect = [[Rect alloc] init];

Objective-C , . BOOL YES NO ( NextStep, Mac OS X).

Objective-C NextStep. Objective-C, Mac OS X.

NS, NextStep.

  NSString  . ( ).

, @"my string" NSString, ( , ).

Company instance- name.

@interface Company : NSObject
{
     NSString *name;
}

, Objective C 2.0. @property.

@property (retain) NSString *name;

instance-. 3 .

  • getter=getterName, , instance-.
  • setter=setterName, , instance-.

/

  • readwrite  , .
  • readonly  .

.

  • assign  . POD- , .
  • retain  , , instance-, ( ).
  • copy  , .

GC assign, retain, copy . , , :

@synthesize name;

instance- .

, , .

[]

Objective-C @.

C++, ( h,   cpp).

:

@interface ClassName : SuperClass
{
    instance variable declarations
}
 
method declarations
@end

runtime Apple   NSObject, .

:

Apple, NSObject Object (#import <objc/Object.h>).

@interface Rect : NSObject
{
        float     width;
        float     height;
        BOOL      isFilled;
        NSColor * color;
}
@end

C++ Smalltalk.

. , ( class object, ). C++.

  . , Objective-C , .

Rect.

@interface Rect : NSObject
{
        float     x, y;
        float     width;
        float     height;
        BOOL      isFilled;
        NSColor * color;
}
+ newRect;
- (void) display;
- (float) width;
- (float) height;
- (float) area;
- (void) setWidth: (float) theWidth;
- (void) setHeight: (float) theHeight;
- (void) setX: (float) theX y: (float) theY;
@end

, instance- (, width height).

( ). , , id.

, ( ) .

Objective-C   oneway, in, out, inout, bycopy byref. . ( NextStep 90- ).

, , :

- makeGroup: (id) object, ...;

Objective-C #include #import, #include, , .

, , ( , ).

@class, , .

@class Shape, Rect, Oval;

:

#import "ClassName.h"
 
@implementation ClassName
 
    method implementations
 
@end

Rect, .

#import "Rect.h"
 
@implementation Rect
 
+ newRect
{
        Rect * rect = [[Rect alloc] init];
 
        [rect setWidth:  1.0f];
        [rect setHeight: 1.0f];
        [rect setX: 0.0f y: 0.0f];
 
        return rect;
}
 
- (float) width
{
   return width;
}
 
- (float) height
{
   return height;
}
 
- (float) area
{
   return [self width] * [self height];
}
 
- (void) setWidth: (float) theWidth
{
   width = theWidth;
}
 
- (void) setHeight: (float) theHeight
{
   height = theHeight;
}
 
- (void) setX: (float) theX y: (float) theY
{
   x = theX;
   y = theY;
}
 
@end

, instance-. , C++, ( ) @private, @protected @public ( C++).

@interface Worker : NSObject
{
        char * name;
@private
        int    age;
        char * evaluation;
@protected
        int    job;
        float  wage;
@public
        id     boss
}

public , -> ( objPtr -> fieldName).

[]

, [object msg] objc_msgSend. - , . . , . , objc_msgSend ,  . . .

Objective-C isa  class object . class object , isa .

class object class object (superclass) dispatch table. , ().

, objc_msgSend dispatch table . , dispatch table  . .

( ) , .

  «» NSInvocation forwardInvocation:, NSInvocation.

forwardInvocation:, , :

- (void)forwardInvocation:(NSInvocation *)anInvocation
{
    if ( [someOtherObject respondsToSelector: [anInvocation selector]] )
        [anInvocation invokeWithTarget: someOtherObject];
    else
       ..........
}

dispatch table , . . 32- , .

SEL , .

@selector():

   SEL setWidth = @selector(setWidth:);
   SEL setPos   = @selector(setX:y:);

( ) NSSelectorFromString NSStringFromSelector:

   SEL        setWidth   = NSSelectorFromString ( @"setWidth:" );
   NSString * methodName = NSStringFromSelector  ( setPos );

Objective-C respondsToSelector::

    if ( [anObject respondsToSelector: @selector(setWidth:)] )
         [anObject setWidth: 200.0];

, ( , , ), performSelector:, performSelector: withObject:, performSelector: withObject: withObject: performSelector::withObject: withObject: withObject:.

    [myObject performSelector:sel withObject: nil];

, performSelector: id.

, class. Class.

    Class    * cls     = [anObject class];
    NSString * clsName = NSStringFromClass ( cls );

class object :

    Class * cls = NSClassFromString ( clsName );

  self _cmd.

this,   .   .

self , :

- (float) area
{
   return [self width] * [self height];
}

self ,   super. super   . super dispatch table , dispatch table .

, super , .

Objective-C ( ).

  (self) (_cmd).

methodForSelector: .

typedef float (*WidthFunc)( id, SEL );
typedef void  (*SetWidthFunc)( id, SEL, float );
 
WidthFunc    widthFunc    = (WidthFunc)    [myRect methodForSelector: @selector (width)];
SetWidthFunc setWidthFunc = (SetWidthFunc) [myRect methodForSelector: @selector (setWidth:)];
 
(*setWidthFunc)( myRect, @selector (setWidth:), 27.5f );

, .

[]

Objective-C ( C++ , ). . , , .

, .

:

@protocol ProtocolName
method declarations
@end

Serializable :

@protocol Serializable
- (id)   initWithCoder: (NSCoder *) coder;
- (void) encodeWithCoder: (NSCoder *) coder;
@end

:

@protocol MyProto <Protocol1, Protocol2, Serializable, Drawable>

, :

@interface MyClass : SuperClass <Protocol1, Protocol2, Serializable, Drawable>

, , conformsToProtocol::

if ( [myObject conformsToProtocol: @protocol (Serializable)] )
     [myObject encodeWithCoder: myCoder];

, () ().

, myObject , Serializable Drawable, :

id <Serializable,Drawable>  myObject;

, , myObject , Shape Serializable, :

Shape <Serializable>  *myObject;

, , .

, Objective-C ( Protocol):

Protocol * myProto = @protocol ( Serializable );

:

@protocol MyProto, Serializable, Drawable;

, MyProto, Serializable Drawable , .

[]

Objective-C , C++ Java.

@try, @catch, @finally @throw.

 Cup * cup = [[Cup alloc] init];
 
 @try
 {
     [cup fill];
 }
 @catch ( NSException * exc )
 {
    NSLog ( @"Exception caught: %@", exc );
 }
 @catch ( id exc )
 {
    NSLog ( @"Unknown exception caught" );
 }
 @finally
 {
    [cup release];
 }

@throw, -. Mac OS X/NextStep NSException.

 NSException * exc = [NSException exceptionWithName: @"my-exception" reason: @"unknown-error"
                                  userInfo: nil];
 @throw exc;

@catch- @throw (rethrowing exception).

[]

Objective-C . @synchronized () .

@synchronized () Objective-C ( , self), (mutex).

, - . , , @synchronized ().

, , , (suspended) , . , «» .

, .

- (void) criticalMethod
{
    @synchronized ( self )
    {
         // perfrom modifications to shared objects
         . . .
    }
}

[]

Objective-C ( new delete). runtime- .

Objective-C NextStep Mac OS X, .

  . alloc ( NSObject), ( NSObject, ). isa class object .

, alloc class object- .

( instance-,  . .) , init. alloc, , .

id anObject = [[Rectangle alloc] init];

. , :

id anObject = [Rectangle alloc];
 
[anObject init];

, init ( self).

, , (, , init alloc ) , , , .

alloc, init .

, () init , ( C++,   , , , ).

init init ( [super init]) .

, init, init, initWithName:, initWithContentsOfFile:  . .

init- , designated initializer. init- init .

- (id) initWithName: (const char *) theName   // designated initializer
{
    self = [super init];                        // call inherited method
    if (self)
    {
        name = strdup ( theName );
    }
    return self;
}
 
- (id) init
{
    return [self initWithName: ""];
}

(), NSString , () :

+ (id) stringWithCString:(const char *)cString encoding:(NSStringEncoding)enc
+ (id) stringWithFormat:(NSString *)format, ...

Mac OS X ( NextStep) reference counting  , .

retain ( Foundation , retain).

retain , (), , retain.

, release.

, , .

dealloc, . [super dealloc].

- (void) dealloc
{
    . . .
    [super dealloc];
}

[]

[]

Objective C « ». Objective C :

  • , «alloc», «new» «copy». , alloc, newObject, mutableCopy.
  • , , «release» «autorelease». .
  • , ( retain), (, «copy»).

Objective C , , .

[]

, Company, workers.

@interface Company : NSObject
{
    NSArray *workers;
}
-(NSArray*)workers;
@end

:

Company *company = [[Company alloc] init];
// ...
NSArray *workers = [company workers];
// ...
[company release];

Company , ([company release]). , workers , . , .

Convenience

, convenience ; +className , , Objective C.

Company *company = [Company company];
[company release];

[company release] , autorelease .

company:

+(Company*)company
{
     id ret = [[Company alloc] init];
     return [ret autorelease];
}
autorelease

workers Company. , , workers :

-(NSArray*)workers
{
     NSArray *copy = [[NSArray alloc] initWithArray:workers];
     return [copy autorelease];
}

autorelease copy autorelease , release , . , autorelease , release , autorelease .

, , NSData initWithContentsOfURL:options: error: error (NSError **)errorPtr. , , , , .

, . -(void)dealloc. - , .

-(void)dealloc
{
    [workers release];
    [super dealloc];
}

, release, dealloc . , dealloc .

dealloc. , . , dealloc , ,  . .

[] Autorelease pool

Autorelease , release . , autorelease , autorelease.

Cocoa autorelease . -AppKit autorelease .

Autorelease NSAutoreleasePool.

int main (int argc, const char * argv[])
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
 
     Company *company = [Company company];
     NSArray *workers = [company workers];
 
    [pool drain];
    return 0;
}

autorelease release, drain. release drain . GC drain objc_collect_if_needed.

Autorelease

Cocoa autorelease . autorelease release.

Autorelease . autorelease , .

[]

Objective C . , , copy, NSObject. copyWithZone NSCopying. NSObject NSCopying -.

: (shallow copy) (deep copy). , , . .

, - NSCopying. , NSCopying:

@interface Company : NSObject <NSCopying>
{
     NSString *name;
}
@property(retain) NSString *name;
-(id)copyWithZone:(NSZone *)zone;
@end
 
@implementation Company
@synthesize name;
-(id)copyWithZone:(NSZone *)zone
{
     id copy = [[[self class] allocWithZone:zone] init];
     [copy setName:[self name]];
     return copy;
}
@end

NSCopying, : allocWithZone copyWithZone.

id *copy = [super copyWithZone:zone];

immutable , retain.

-(id)copyWithZone:(NSZone *)zone
{
     return [self retain];
}

[]

Objective-C . Ruby, C#, JavaScript . , . NSObject .

, ( , instance- ), .

, , . :

#import "ClassName.h"
@interface ClassName ( CategoryName )
  methods declarations
@end

:

#import "CategoryName.h"
@implementation ClassName ( CategoryName )
  methods bodies
@end

(property), readwrite :

@interface ClassName
{
  BOOL flag;
}
@property (assign, readonly) BOOL flag;
@end
 
#import "ClassName"
@implementation ClassName () //  
@property (assign, readwrtite) BOOL flag;
@end
 
@implementation ClassName
@synthesize flag;
 
-(void) someAction
{
  self.flag = YES;
}
@end

, - , :

@protocol Printable // ,   
-(void) print;
@end
 
@interface NSString(Printable) <Printable> //    NSString   
@end
 
@implementation NSString(Printable) //   
-(void) print
{
  NSLog(@"  %@!", self);
}
@end

- PrintableString NSString

[] Class objects Objective-C runtime

Objective-C class object  , , , , instance-.

, , .

class object , NSObject, , , , instance- NSObject.

class object  class object () initialize.

class object, , . Singleton  initialize static-.

Objective-C runtime Apple, -, ( ).

:

Method   class_getInstanceMethod( Class aClass, SEL aSelector );
Method   class_getClassMethod   ( Class aClass, SEL aSelector );
struct objc_method_list * class_nextMethodList(Class theClass, void ** iterator);
void     class_addMethods       ( Class aClass, struct objc_method_list * methodList );
void     class_removeMethods    ( Class aClass, struct objc_method_list * methodList );
unsigned method_getNumberOfArguments ( Method method );
unsigned method_getSizeOfArguments   ( Method method );
unsigned method_getArgumentInfo      ( Method method, int argIndex, const
                                       char ** type, int *  offset );
Ivar     class_getInstanceVariable   ( Class aClass, const char * aVariableName );

class_getInstanceMethod (objc_method), instance- .

class_getClassMethod (objc_method), .

class_nextMethodList . .

    void                    * iterator = 0;
    struct objc_method_list * methodList;
 
    //
    // Each call to class_nextMethodList returns one methodList
    //
 
    methodList = class_nextMethodList( classObject, &iterator  )
 
    while ( methodList != nil )
    {
        // do something with the method list here
 
        methodList = class_nextMethodList ( classObject, &iterator  );
    }

class_addMethods .

class_removeMethods .

method_getNumberOfArguments .

method_getSizeOfArguments , .

method_getArgumentInfo ..

class_getInstanceVariable instance- objc_ivar.

, . @encode ().

char * buf1 = @encode ( int ** );
char * buf2 = @encode ( struct key );
char * buf3 = @encode ( Rectangle );

[]

Apple.[1]

Objective-C -[2] [3].

GNUstep open-source Objective-C, Foundation AppKit NextStep Mac OS X.

GNUstep Objective-C , .

gcc Objective-C, GNU/Linux .

Objective-C MS Windows c POSIX (mingw, cygwin) POSIX (MS SFU, Services For Unix, www.microsoft.ru  Microsoft Windows UNIX), .

[]

  1. Apple Developer
  2. comp.lang.objective-c
  3. Objc-language

[]

[]

    (  IDE    )

IEC 61131-3
   
Borland Turbo C  Clang  GCC  LCC  Pelles C  PCC  TCC  Visual C++ (C++/CLI  C++/CX)  Watcom C/C++ compiler
  glibc  dietlibc  uClibc  Newlib  Eglibc  Bionic
C-       
C++  C#  D  Objective-C  Alef  Limbo  Go  Vala
C C C++ (  )  Pascal C  C - Java
Category :
«/w/index.php?title=Objective-C&oldid=44249134»