Objective-C Quinton Palet

Introduction  Objective-C was developed to bring large scale software development the power of the object-oriented approach  Comprised of C and Smalltalk  Strict superset of C

History  Early 1980’s – Brad Cox and Tom Love develop Objective-C at Stepstone  1985 – Steve Jobs leaves Apple and starts NeXT  1986 – Stepstone releases Objective-C  1988 – Steve Jobs licensed Objective-C for NeXT  1996 – Apple buys NeXT  1999 – Apple releases OS X  2007 – Apple releases iOS and Objective-C 2.0

Growing Popularity  From 5 th to 3 rd on the TIOBE programming community index  Apple gaining more market share in PC market  iPhone, iPad, iPod Touch, and Apple TV 

Environments  Windows  GCC under Cygwin or MinGW  Linux  GNU compiler  Mac  Xcode

Frameworks  Collection of classes  Provide methods beyond the core methods  Frameworks often contain other Frameworks

Cocoa & Cocoatouch  Most popular frameworks  Cocoa  Foundation framework  CoreData framework  AppKit framework  Cocoatouch  Foundation framework  CoreData framework  UIKit framework

File Declarations  Declared by file type .h Interface .m Implementation .nm Implementation with C++ code along with Objective-C and C code

Syntax  Strict superset of C  Can compile C code without any linkage  Commenting the same  // single line  /* block */

Data types and Variable  Objective-C by itself has  Int  Float  Double  Char  BOOL  With frameworks has access to much more  Objective-C 2.0 Added  Int (signed/unsigned)  Short  Long  Long Long  Id

Data types and Variables cont.  Using Foundation.framework you can define a string: NSString *someString world”;  * represents that it is a pointer NSString *SecondString = [[NSString alloc] self.name];

Syntax - Functions  Declare method in interface file or.h + (return_type) classMethod1; -(return_type) classMethod2: (param1_type) param1_name; + similar to a static function in Java - similar function called on instance of class - (void)insertObject: (id)someObject atIndex: (int) index;

Syntax – Functions cont.  Implementation similar to C++ using the interface declaration  Done in the.m or.nm file + (return_type) classMethod: (paramType) paramName { Return (return_type) returnName; }

Functions cont.  Objective-C does not allow for Function overloads  This makes it so Objective-C isn’t able to easily implement polymorphism  Where as Java can implement constructors like: public initPerson(){ name = DEFAULTNAME; } Public initPerson(String inName){ name = inName; }

Functions Cont.  In order to do this in Objective-C you would have to implement different method names like: -(void) initPerson { name = [[NSString alloc] initWithString:DEFAULTNAME]; } -(void) initPersonWithName: (NSString *) inName{ name = [[NSString alloc] initWithString: inName]; }

Functions Cont.  Objective-C does not allow for Operator overloads  In turn Objective-C does not allow ad-hoc polymorphism  Example in C++ or C#: Time Time::operator+(const Time& addTime) { Time temp = *this; temp.seconds += addTime.seconds; temp.minutes += temp.seconds / 60; temp.seconds %= 60; temp.minutes += addTime.minutes; temp.hours += temp.minutes / 60; temp.minutes %= 60; temp.hours += addTime.hours; return temp; }  Allows you to do: sumTime = firstTime + secondTime;

Functions Cont.  Simple Solution make a function that does what you would want the operator overload to do. -(void) addTime: (Time) inTime{ self.seconds += inTime.seconds; self.minutes += self.seconds / 60; self.seconds %= 60; self.minutes += inTime.minutes; self.hours += self.minutes / 60; self.minutes %= 60; self.hours += inTime.hours; } So can be called by [timeOne addTime: timeTwo];

Messages  Messages are similar to a method call in C++ or Java Object *O = [Object messagePassed: Param];  Message passing allows dynamic typing  Allows postponing a messages destination until runtime  If class can’t handle the message it can forward it, hold onto it, or silently ignore it - (void) setValue: (id) Obj;  Obj can be any class

Memory Management  No built in memory management  Must allocate or alloc memory for objects NSString str = [[NSString alloc] init];  Can retain memory to pass objects NSString str = [[[NSString alloc] init] retain];  Developer responsible for releasing objects [str release];

Memory Management  Autoreleasepool allows you to group objects and release them all at once or “drain” the pool NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; // create autoreleased objects NSString str = [[[NSString alloc] init] autorelease]; [pool release];

Objective-C 2.0  Added in  Garbage collection  Modern runtime  Fast enumeration Replaced: NSEnumerator *enumerator = [someCollection objectEnumerator]; someObject *O While ((O = [enumerator nextObject]) != nil) { [O name]; } With: for( someObject *O in someCollection) { name]; }  dot syntax Without dot syntax: [someClass objectAt: 0 With dot syntax:someClass[0].name

Objective-C 2.0 cont.  Added in Property variables Can be implemented or (nonatomic) propertyType * (nonatomic, readonly, getter = timestamp) propertyType * propertyName2;

Objective-C 2.0 cont. So (nonatomic) propertyType * (nonatomic, readonly, getter = propertyName) propertyType * propertyName2; Turns into Event{ propertyType * propertyName; propertyType * propertyName2; Event{ -(propertyType) propertyName{ return propertyName; } -(void) setPropertyName: (propertyType) in { _propertyName = in; } -(propertyType)propertyName2{ return [self propertyName]; }

Objective-C 2.0 cont.  You can choose to dynamically do your properties getter and setter methods also, for (nonatomic) propertyType propertyName; propertyName; // need this because it lets the compiler know you will implement // your own getter and setter methods for the property -(propertyType) propertyName { return propertyName; } -(void) setPropertyName: (propertyType) inValue { propertyName += inValue; }

Automatic Reference Counting  Garbage collection was deprecated  Developer no longer needs to manually manage retain and release  Retain and release added in by compiler at compile time  Removed the overhead of a separate process managing retain counts

Objective-C or Java  Both have benefits to learning them, and are the two of the most popular languages for mobile development.  Both are in the top 4 of the TIOBE index  Java has a written standard  Objective-C has no written standard but is heavily documented by Apple  Java is supported on more devices where as Objective-C is primarily Apple devices.  Java has IDEs for all major operating systems where as Objective-C is only on Mac OS X

Objective-C or Java cont.  Objective-C can be more readable than Java  Objective-C is a more dynamic language  Allows you to easily add onto programs due to dynamic typing  Objective-C programs tend to be larger due to compiler not being able to strip methods or make them inline because of the dynamic typing you wont know what methods are needed until runtime.  Objective-C does not allow operator overloading, function overloading, and multiple inheritance.  Objective-C doesn’t waste resources on a garbage collector  In order to add an Objective-C app to their marketplace it must go through a screening and you need a developers license, Java has open marketplaces and also requires no developers license

Objective-C or Java cont.  Overall I would say Java is a more useful language to learn rather than Objective-C  Doesn’t mean there’s no benefit to learning Objective-C  Apple has a large market share in PC, mobile phones, and tablets.  You can use other languages to develop for OS X and iOs  Such as C++ and Ruby  Many times still need to use the Cocoa framework to add the necessary functionality  Makes it so you’re still developing in Objective-C and only adding another layer in below the application making it less efficient

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References  [1] Kaul, Vivek. (2009, May 11). What Jobs did when he was fired from Apple. Retrieved from apple_  [2] Biancuzzi, F., & Warden, S. (2009). Masterminds of programming: Conversations with the creators of major programming languages. Sepastopol, CA: O'Reilly Media.  [3] Apple. (2010, December 13). Cocoa fundamentals guide. Retrieved from mentals/Introduction/Introduction.html  [4] Apple. (2011, October 12). The objective-c programming language. Retrieved from ntroduction/introObjectiveC.html  [5] LLVM. (2012). Automatic Reference Counting. Retrieved from  [6] TIOBE Software. (2012, November). TIOBE programming community index for November Retrieved from