Objective-C

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# Objective-C 
#### Un aperçu historique

.footnote[[github.com/n-b/objc-history](http://github.com/n-b/objc-history)]

*(Partiel et subjectif)*

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## C & SmallTalk

## Brad Cox & Tom Love

## Stepstone

## gcc

## NeXT

##### NeXTSTEP, OPENSTEP, GnuStep

## Apple

## clang

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# NeXT

*“How much does Stepstone charge for the PC version of Obj-C ? And, does it run on a 286 ?”*

*comp.sys.next.programmer, 1992*

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## NeXT

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#### Style

La plupart des méthodes retournent `self`.

@interface SomeClass

- (id) doThis;
	- (id) doThat;

@end

...
	
	[[someObject doThis] doThat];

---
#### Style

id est le type par défaut.

@interface SomeClass

- method: arg;

@end
	
	@implementation SomeClass

- method: arg
	{
		//
	    return someObject;
	}

@end

---
#### “Cocoa”

* Interface Builder et AppKit
	* (Xcode s’appelle Project Builder)
* IBOutlets and IBActions
* Target-Action
* Responder Chain

---
#### NeXTSTEP 4.0, 1994

* Préfixe `NS`

<!--
 Le préfixe des classes Next, "NX", devient NS à la création de Foundation.

NXApp est renommé NSApp, par exemple.
 Surtout, `NSObject` remplace `Object`

-> C'est le split principal entre avec GnuStep, qui continue d'utiliser Object et implémentera petit à petit les méthodes de Foundation.
 -->

* Gestion “Semi-Automatique” de la mémoire

- (id) retain;
    - (void) release;
    - (id) autorelease;

--
	
* Sur GnuStep, les `Object`s ont une méthode `free`, comme en c++.

---
#### Foundation

* NSSelectorFromString, NSClassFromString, etc.
* NSInvocation
* NSProxy

---
#### Enterprise Objects Framework

* Key-Value Coding via le protocole `EOFKeyValueCoding`

- (void) valueForKey:(NSString*)key;
	- (void) setValue:(id)value forKey:(NSString*)key;

* WebObjects

* Renaîtra sur Mac en tant que **CoreData**.

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# Apple

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## Apple

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Rachat de NeXT en 1997.

*“Cocoa is [now] owned by Apple, and the indications are that Apple is going to either completely drop its support for ObjC in favor of Java, or at least de-emphasize its use to the point where nobody would want to even look at it (in fact, this "death by default" has already happened).”*

comp.sys.next.programmer, Avril 2000.

--
Apple a plusieurs plans :

* Carbon et CoreFoundation

* JavaCocoa

---
#### Toll-Free Bridging (Mac OS X 10.0)

NSString * <=> CFStringRef

`objc_getfutureclass` : Used by CoreFoundation's toll-free bridging. Do not call this function yourself.

---
#### Exceptions Modernes (Mac OS X 10.3)

NS_DURING
		[[NSException exception] raise];
	NS_HANDLER
	   // handle it
	NS_ENDHANDLER

@try
		@throw exception
	@catch
		// handle it
	@finally

---
#### Key-Value Observing et Bindings (Mac OS X 10.3)

[object addObserver:self forKeyPath:@"someKey" options:0 context:NULL];

--

`objc_duplicateclass` : Used by Foundation's Key-Value Observing. Do not call this function yourself.

---
## CoreData (Mac OS X 10.4)

#### Key-Value Coding sur les Collections

[array valueForKey:@"someValue"]

#### Opérateurs KVC sur les Collections

[persons valueForKeyPath:@"@avg.age"];
	[array valueForKey:@"someValue"]

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# Mac OS X 10.5
# Objective-C 2.0

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## Objective-C 2.0

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#### Garbage Collector

D’après Apple, “State of the art”.

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#### Notation pointée

[obj setFoo:value]

devient

obj.foo = value;

#### Properties

- (Foo*) foo;
	- (void) setFoo:(Foo*)foo;
	
devient

@property Foo* foo;

---
#### Fast Enumeration

--
	
	NSEnumerator * e
	
    NSEnumerator * enumerator = [array objectEnumerator];
    NSObject * object = nil;
	
    while ( (object = [enumerator nextObject]) != nil )
	{
        ...
    }
	
--

for( NSObject* object in array)
	{
		...
	}

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#### “Modern runtime”

Uniquement sur Mac 64-bit et sur iOS.

**Non-fragile ABI**

@defs et sizeof(NSArray) n’ont plus de sens.

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#### Bonus

* JavaCocoa deprecated.

* Bridges du runtime avec d’autres languages : rubyCocoa, python (pyObjC), AppleScript…

* `@optional` methods in Protocols.

* Class Extentions (“catégorie anonyme”)

// SomeClass.m
	@interface SomeClass(PrivateMethods)
	...
	@end
	
	// devient

// SomeClass.m
	@interface Class()
	...
	@end

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# Clang

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## Clang

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#### Clang Static Analyzer (Xcode 3)

Détection automatique de leaks et de bugs, basée sur les conventions du language.

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#### Blocks (“Objective-C 2.1”)

Ajout à `C`, mais les blocks sont utilisables comme des objets Objective-C.

__block BOOL found = NO;
	NSSet *aSet = [NSSet setWithObjects: @"Alpha", @"Beta", @"Gamma", @"X", nil];
	NSString *string = @"gamma";
 
	[aSet enumerateObjectsUsingBlock:^(id obj, BOOL *stop) {
	    if ([obj localizedCaseInsensitiveCompare:string] == NSOrderedSame) {
	        *stop = YES;
	        found = YES;
	    }
	}];
 
	// At this point, found == YES

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## LLVM Compiler 3.0

---

#### Private Instance Variables

// SomeClass.h
	@interface SomeClass : NSObject
	{
		int foo;
		id bar;
	}
	...
	@end

devient

// SomeClass.m
	@interface SomeClass ()
	{
		int foo;
		id bar;
	}
	...
	@end

---

#### Private Instance Variables

// SomeClass.h
	@interface SomeClass : NSObject
	{
		int foo;
		id bar;
	}
	...
	@end

ou même

@implementation SomeClass
	{
		int foo;
		id bar;
	}
	...
	@end

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#### ARC

--

* Garbage Collector deprecated

* `retain` et `release` sont intégrés au language.

* `objc_method_family`

* `weak` pointers mis à nil automatiquement

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## LLVM Compiler 4.0

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#### `@synthesis` automatique des ivars des properties

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#### Boxing
	
	[NSNumber numberWithDouble:M_PI/2.0]
	
devient
	
	@(M_PI/2.0)

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#### Container literals

pour `NSArray` et `NSDictionary

[NSArray arrayWithObject:obj1, obj2, obj3, nil];
	
devient
	
	@[obj1, obj2, obj3]

---

#### Subscripting

[dictionary objectForKey:@"key"];
	
devient

dictionary[@"key"]

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#### Bonus

* Mot clé `instancetype`

@interface A
	+ (instancetype)constructAnA;
	@end

[[NSMutableArray new] addObject:someObject];

* Function Overloading in C

float __attribute__((overloadable)) tgsin(float x) { return sinf(x); }
	double __attribute__((overloadable)) tgsin(double x) { return sin(x); }
	
--

* CoreFoundation “compatible” avec ARC : `arc_cf_code_audited`.

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# Futur ?

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* Appel à "`super`" automatique, sans respécifier les arguments. (par exemple pour viewDidAppear:)

* `-[NSString stringWithFormat:]` plus court

* Boxing pour NSValue
	 
	 
	`[NSValue valueWithCGPoint:CGPointMake(10,20)];` 
	 
	 
	`@( CGPointMake(10,20) )`

* Namespaces

* Attribut de méthode pour le *designated initializer*

* Méthodes protected et marquées pour réimplémentation

* Valeurs de paramètres par défaut

- (void) doSomething;
	- (void) doSomethingWithStuff:(Stuff*)s;

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# Links

* [comp.sys.next.programmer](https://groups.google.com/forum/?fromgroups=#!topic/comp.sys.next.programmer/NUXThBOc360)
* [Objective-C Feature Availability Index](http://developer.apple.com/library/ios/#releasenotes/ObjectiveC/ObjCAvailabilityIndex/_index.html)
 
 
* [The OPENSTEP Development Environment](http://objc.toodarkpark.net/introobj.html#712)
* [MacTECH : C++ Versus Objective-C](http://www.mactech.com/articles/mactech/Vol.13/13.03/CandObjectiveCCompared/index.html)
* [GnuStep ObjectiveC Book](http://www.gnustep.org/resources/documentation/ObjectivCBook.pdf)
* [History of Cocoa and Objective-C](http://www.cocoacast.com/cocoacast/?q=node/14)
* [Objective-C Runtime Reference](http://developer.apple.com/library/ios/ipad/#documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html)
* [Clang Language Extensions](http://clang.llvm.org/docs/LanguageExtensions.html#objc_features)