Embed Size (px)
Citation preview
Objective-CQuinton 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 5th to 3rd on the TIOBE programming community index
Apple gaining more market share in PC market
iPhone, iPad, iPod Touch, and Apple TV
http://www.apple.com/ios/videos/#developers/
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 = @”hello world”;
* represents that it is a pointer
NSString *SecondString = [[NSString alloc] initWithFormat:@”hello, %@”, 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 JavaObject *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) {
NSLog(@”%@”, [O name];
}
With:for( someObject *O in someCollection) {
NSLog(@”%@”,[O name];
}
dot syntaxWithout dot syntax: [someClass objectAt: 0 setName: @”John”];
With dot syntax: someClass[0].name = @”John”
Objective-C 2.0 cont. Added in Property variables
• Can be implemented with @synthesize or @dynamic
@property (nonatomic) propertyType * propertyName;
@property (nonatomic, readonly, getter = timestamp) propertyType * propertyName2;
@synthesize propertyName;
@synthesize propertyName2;
Objective-C 2.0 cont.So this:
@property (nonatomic) propertyType * propertyName;
@property (nonatomic, readonly, getter = propertyName) propertyType * propertyName2;
@synthesize propertyName;
@synthesize propertyName2;
Turns into this:@interface Event{
propertyType * propertyName;
propertyType * propertyName2; }
@implementation Event{
-(propertyType) propertyName{
return propertyName; }
-(void) setPropertyName: (propertyType) in {
_propertyName = in; }
-(propertyType)propertyName2{
return [self propertyName]; }
}@end
Objective-C 2.0 cont. You can choose to dynamically do your properties getter and setter methods
also, for example:@interface Event{
@property (nonatomic) propertyType propertyName;
}
@implementation Event{
@dynamic 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;
}
}@end
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
http://www.youtube.com/watch?v=OpNBbdA3jq0
Questions ?
References [1] Kaul, Vivek. (2009, May 11). What Jobs did when he was fired from Apple. Retrieved from
http://www.dnaindia.com/money/report_what-steve-jobs-did-when-he-was-fired-from-apple_1254757
[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 https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CocoaFundamentals/Introduction/Introduction.html
[4] Apple. (2011, October 12). The objective-c programming language. Retrieved from https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjectiveC/Introduction/introObjectiveC.html
[5] LLVM. (2012). Automatic Reference Counting. Retrieved from http://clang.llvm.org/docs/AutomaticReferenceCounting.html
[6] TIOBE Software. (2012, November). TIOBE programming community index for November 2012. Retrieved from http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html
