Difference between revisions of "Objective-C"

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Objective-C is a superset of C language and it is called objective-c because it is a object-oriented language. It is used to build Cocoa and Cocoa Touch apps.
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On 2 March 2013, I attended a slightly haphazard course "Become a NSZombie, Introduction to iOS" at Plug-In@Blk71.
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http://30d.me/challenge/ios/
  
 
=== What one needs in order to program in Objective-C ===
 
=== What one needs in order to program in Objective-C ===
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* Compiler (Xcode)
 
* Compiler (Xcode)
 
* Program to design the interface (Interface Builder - which is now built into Xcode)
 
* Program to design the interface (Interface Builder - which is now built into Xcode)
−
* Debuggers (Instruments)
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* iOS simulator (simulate apps)
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* Debuggers (Instruments - monitor performance)
  
 
=== Get Xcode ===
 
=== Get Xcode ===
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* [https://developer.apple.com/xcode/ Download xcode]
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== Basics ==
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=== Data types in Objective-C ===
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* int (integer) [ObjC NSNumber]
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* unsigned int [ObjC NSNumber]
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* float (floating point number) [ObjC NSNumber]
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* double (double precision) [ObjC NSNumber]
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* char (a, b, c - single character)
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* string ("a string")
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* bool (true/false)
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* arrays (NSArray)
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* key value pair (eg: courseName = iOS)
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<pre>operators still apply as expected
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== check if equal
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|| or
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&& and
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</pre>
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=== Objective C Classes ===
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Instead of calling a method you pass a message to objects.
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A class is a collection of objects with similar behaviour and properties. Objects of same class have simlar behaviour and properties.
 +
 +
Most common classes:
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* NSInteger
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* NSNumber
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* NSString, NSMutableString (you can modify or add things to mutables)
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* NSSet, NSMutableSet
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* NSArray, NSMutableArray
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* NSDictionary, NSMutableDictionary
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 +
=== Initialisation ===
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* int myInteger;
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* int myInteger = 42;
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* int myInteger, myInteger2, myInteger3;
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=== Operators ===
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* operators - as normally expected except there is also "modulo"
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* % - result will be the remainder from the integer division of the 1st by the 2nd
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* (only for int or long, insert some caveat here about floats and doubles and using [http://www.cplusplus.com/reference/cmath/fmod/ fmod])
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* eg: int moduloResult = a % b;
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=== NSLog ===
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String Formatters for the trace/nslog:
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==== Hello World ====
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NSLog(@"Hello World!");
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==== Commenting ====
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<pre>
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//commenting
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/* a really long
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comment */
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</pre>
  
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==== Debugging Variables ====
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<pre>NSLog(@" a %% b = %i", c)
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c = b % a;</pre>
  
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<pre>int myNum = 7;
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NSString *myString = @"Dog";
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NSLog(@"The number is %i and the string is %@.", myNum, myString);</pre>
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If you want a % sign you have to put in %%.
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<pre>NSLog(@"%@", [NSNumber numberWithInt:i]);
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%@ Object
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%d, %i signed int
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%u    unsigned int
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%f    float/double
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%1.2f to specific number of decimals
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%x, %X hexadecimal int
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%o    octal int
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%zu    size_t
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%p    pointer
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%e    float/double (in scientific notation)
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%g    float/double (as %f or %e, depending on value)
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%s    C string (bytes)
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%S    C string (unichar)
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%.*s  Pascal string (requires two arguments, pass pstr[0] as the first, pstr+1 as the second)
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%c    character
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%C    unichar
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%lld  long long
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%llu  unsigned long long
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%Lf    long double
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</pre>
  
 
== See also ==
 
== See also ==
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* http://mobile.tutsplus.com/tutorials/iphone/learn-objective-c-day-1/
 
* http://mobile.tutsplus.com/tutorials/iphone/learn-objective-c-day-1/
 
* http://cocoadevcentral.com/d/learn_objectivec/
 
* http://cocoadevcentral.com/d/learn_objectivec/
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 +
[[Category:Programming]]

Latest revision as of 02:37, 12 July 2013

Objective-C is a superset of C language and it is called objective-c because it is a object-oriented language. It is used to build Cocoa and Cocoa Touch apps.

On 2 March 2013, I attended a slightly haphazard course "Become a NSZombie, Introduction to iOS" at Plug-In@Blk71.

http://30d.me/challenge/ios/

What one needs in order to program in Objective-C

  • Source Code Editor (Xcode)
  • Compiler (Xcode)
  • Program to design the interface (Interface Builder - which is now built into Xcode)
  • iOS simulator (simulate apps)
  • Debuggers (Instruments - monitor performance)

Get Xcode

Basics

Data types in Objective-C

  • int (integer) [ObjC NSNumber]
  • unsigned int [ObjC NSNumber]
  • float (floating point number) [ObjC NSNumber]
  • double (double precision) [ObjC NSNumber]
  • char (a, b, c - single character)
  • string ("a string")
  • bool (true/false)
  • arrays (NSArray)
  • key value pair (eg: courseName = iOS)
operators still apply as expected
== check if equal
|| or
&& and

Objective C Classes

Instead of calling a method you pass a message to objects. A class is a collection of objects with similar behaviour and properties. Objects of same class have simlar behaviour and properties.

Most common classes:

  • NSInteger
  • NSNumber
  • NSString, NSMutableString (you can modify or add things to mutables)
  • NSSet, NSMutableSet
  • NSArray, NSMutableArray
  • NSDictionary, NSMutableDictionary

Initialisation

  • int myInteger;
  • int myInteger = 42;
  • int myInteger, myInteger2, myInteger3;

Operators

  • operators - as normally expected except there is also "modulo"
  •  % - result will be the remainder from the integer division of the 1st by the 2nd
  • (only for int or long, insert some caveat here about floats and doubles and using fmod)
  • eg: int moduloResult = a % b;

NSLog

String Formatters for the trace/nslog:

Hello World

NSLog(@"Hello World!");

Commenting

//commenting

/* a really long
comment */

Debugging Variables

NSLog(@" a %% b = %i", c)
c = b % a;
int myNum = 7;
NSString *myString = @"Dog";
NSLog(@"The number is %i and the string is %@.", myNum, myString);

If you want a % sign you have to put in %%. 

NSLog(@"%@", [NSNumber numberWithInt:i]);

%@ Object
%d, %i signed int
%u     unsigned int
%f     float/double
%1.2f to specific number of decimals
%x, %X hexadecimal int
%o     octal int
%zu    size_t
%p     pointer
%e     float/double (in scientific notation)
%g     float/double (as %f or %e, depending on value)
%s     C string (bytes)
%S     C string (unichar)
%.*s   Pascal string (requires two arguments, pass pstr[0] as the first, pstr+1 as the second)
%c     character
%C     unichar
%lld   long long
%llu   unsigned long long
%Lf    long double

See also

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