Question

I am working on a ARC based project. I am just wondering what is the main use of self ?

I am having an array as follows

@property(strong,nonatomic)NSMutable *dataArray;

I am initializing the array as follows

-(void)viewDidLoad{

 self.dataArray=[[NSMutableArray alloc]initWithObjects:@"one",@"two",nil];  //first method

}

or

-(void)viewDidLoad{

 dataArray=[[NSMutableArray alloc]initWithObjects:@"one",@"two",nil];  //second method

}

Can anyone tell me what is the difference between my first and second method ?

Answer 1

After lot googling I found the answer to my question ,

@property (nonatomic, retain) NSDate *timestamp;

Objective C will generate the getter and setter as follows

(NSDate *)timestamp
{
   return timestamp;
}

(void)setTimestamp:(NSDate *)newValue
{
   if (timestamp != newValue)
   {
      [timestamp release];

      timestamp = [newValue retain];
   }
}

The setter method can be invoked only as follows

self.timestamp = [NSDate date];

where as

timestamp=[NSDate date];

does not invoke the setter method.

Without the self object and the dot we are no longer sending an object a message but

directly accessing the ivar named timestamp.

Conclusion: When we don’t use self , the old value won’t be released ,because the setter

method won’t be invoked i.e Prior to ARC.But in ARC I am not pretty sure about this.As far

as I heard , With ARC either way of setting the ivar is correct as far as memory management

is concerned.