cheat sheets.

= Objective-C cheatsheet (cheat obj_c)

== Comments

  // this is an obj-c comment
  // in this cheatsheet we commented all the optional code


== Sending Messages:

 ---------------------------------------------------------------- 
| Message Type        | Syntax                                   |
 ---------------------------------------------------------------- 
| simple message      | [receiver message]                       |
| named arguments     | [receiver message name1:arg1 name2:arg2] |
| anonymous arguments | [receiver message :arg1 :arg2 ]          |
| typical use         | [receiver message:arg1 name2:arg2]       |
 ---------------------------------------------------------------- 
 
A receiver is an object, a class, self or super. 


== Class Definition 

  @interface classname // (category) <protocols> : superclass
  { 
  @public 
  @protected 
  @private 
      instance variables 
  } 
  method declarations 
  @end 
  
The default visibility of instance variables is @protected. 


== Method Declaration 

 -------------------------------------------------------------------------- 
| Method Type       | Syntax                                               |
 -------------------------------------------------------------------------- 
| instance method   | -(return type) name :(type) arg1 :(type) arg2 //...  |    
| class method      | +(return type) name :(type) arg1 :(type) arg2        |
 --------------------------------------------------------------------------
  
  
== Method Implementation  

  @import “declarations.h” 
  @implementation classname // : superclass 
  -(return type) methodname :(type) arg1 
  { 
      method implementation 
  } 
  @end 


== Protocols 

  @protocol protocolname <protocol list> 
      method declarations 
  @end 


== Exception Handling

  @try 
  { 
  } 
  @catch (exception) // exception is optional
  { 
  } 
  //@finally 
  //{ 
  //} 
  
  @throw(exception);  // throw an exception 
  @throw();  // re-throw current exception 
  
  
== Built-in & pre-defined types 

 -------------------------------
| Type      | Description       |
 -------------------------------
| BOOL      | boolean (YES/NO)  |
| char      | C char            |
| double    | C double          |
| float     | C float           |
| id        | an object         |
| int       | C int             |
| long      | C long            |
| short     | C short           |
| signed    | C signed          |
| unsigned  | C unsigned        |
| void      | no type           |
 -------------------------------


== Thread Synchronization 

  @synchonized(sync object) 
  { 
       // synchronized code 
  } 
  
  
== Special Names 

 -------------------------------------------------------
| Name      | Description                               |
 -------------------------------------------------------
| nil       | the “null” object                         |
| self      | refers to the current object in a method  |
| super     | refers to the superclass in a method      |
 -------------------------------------------------------


== Properties (obj-c 2.0) 

Properties automatically create setter and getter methods for a class 
attribute. They are declared in the method declaration section. 

=== Declaration 

  @property(attributes) type name; 
 
 
=== Attributes 

 -------------------------------------------------------- 
| Attribute   | Description                              | 
 -------------------------------------------------------- 
| readonly    | read-only                                |
| readwrite   | read-write (default)                     |
| assign      | simple assignment (default)              |
| retain      | retain method is invoked upon assignment |
| copy        | use a copy of the object for assignment  |
| nonatomic   | not thread-safe                          |
| getter=name | explicitly name getter                   |
| setter=name | explicitly name setter                   |
 --------------------------------------------------------
  
assign, copy and retain are mutually exclusive. 
The default attributes are assign and readwrite. 
In addition to the normal method invocation syntax, 
dot syntax may be used to access properties: object.property 


=== Implementation 

@synthesize value = variable; 
@dynamic value; 
Fast Enumeration (Objective-C 2.0) 
for (type variable in expression) 
{ 
} 
 
== Common Messages 

 ------------------------------------------------
| Message   | Description                        |      
 ------------------------------------------------    
| alloc     | allocate object memory             |
| init      | initialize object instance         |
| retain    | increment object’s reference count |
| release   | decrement object’s reference count |
 ------------------------------------------------
 

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tnx 2 Ferruccio Barletta (www.the-lazy-programmer.com)