Creating A New Class

Create the new class

Menu > File > New File > iPhone OS > Cocoa Touch> Objective-C class

Subclass of: NSObject

Name it with your class name

Save it in a suitable directory within your project

Setting Up The Class With Basic Properites Etc

In the .h file

#import <Foundation/Foundation.h>

@interface MyClassName : NSObject           //ClassName:SuperclassName
{
    NSMutableArray *SomeArrayName;
    NSMutableString *SomeStringName;
    int SomeIntName;
    BOOL SomeBoolName;
}

@property (nonatomic, retain) NSMutableArray *SomeArrayName;
@property (nonatomic, retain) NSMutableString *SomeStringName;
@property int SomeIntName;
@property BOOL SomeBoolName;

@end
In the .m file

Synthesize any class properties


@implementation MyClassName

@synthesize SomeArrayName, SomeStringName, SomeIntName, SomeBoolName;

An init function should have been created. In it initialise any managed objects


//**************************
//**************************
//********** INIT **********
//**************************
//**************************
- (id)init
{
    self = [super init];
    if (self)
    {
        // Initialization code here.

        SomeArrayName = [[NSMutableArray alloc] init];
        SomeStringName = [[NSMutableString alloc] init];
    }

    return self;
}

Add a dealloc function


//*****************************
//*****************************
//********** DEALLOC **********
//*****************************
//*****************************
- (void)dealloc
{
    [SomeArrayName release];
    [SomeStringName release];

    [super dealloc];
}

Notes About The Class Elements

@interface

Used to  declare a class in objective C

ClassName

The name you are calling the class

SuperclassName

The name of the classes superclass – only single inheritance is permitted so only 1 superclass can be used,  E.g. NSObject

Inside Curley Braces

Declare instance variables

After Closing Curley Brace

Declare any of these in the following order:

properties (@property)

Class methods (start with ‘+’)

Instance methods (start with ‘-‘)

@end

Completes the declaration of the new class

Variables

Class instance variables are declared as normal inside the .h file curley braces, e.g.


	NSString *SomeVariableName1;
	int SomeVariableName2;

Creating Class Properties

To make a variable a property that may be accessed from outside the class add the @property declaration after the class closing curley brace (i.e. with any class method declarations):


}
	@property (nonatomic, readonly) NSString *SomeVariableName1;
	@property int SomeVariableName2;

The following property definitions may be used:

simple (default), copy, retain

How the setter method will set the variable.

readwrite (default), readonly

Can variable be changed

atomic (default), nonatomic

Does variable require a lock.  Atomic=a lock must be acquired to get or set the varaible, nonatomic=no lock is required (and a bit faster).

You also need to ‘synthesize’ the properties inside the .m implementation file:


@implementation ClassName

@synthesize SomeVariableName1, SomeVariableName2;

@end

This tells the compiler to use the standard get and set methods, rather than you having to create the fucntions yourself.

.m Implementation File


@implementation ClassName

@end

All of the method definitions must be inside an implementation block.

Using the class

In the .h file where the class will be used

	ClassName *ClassName1;
In the .m file init where the class will be used

	ClassName1 = [[[self class] alloc] init];

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