Question

So what i want to ask is below

Here is my header file

NSString *myString;

In the m. file

-(void)someMethod{
    myString = [NSString stringWithString = @"Hello"];
    NSLog(@"%@",myString);
}

-(void)dealloc{
    [myString release];
}
-(void)viewDidUnload{
    [myString release];
    myString=nil;
}

Ok now the other situation

In my header file

NSString *myString;
@property (nonatomic,retain) NSString *myString;

In the m. file

@synthesize myString;

-(void)someMethod{
    NSString *tempString = [[NSString alloc] initWithString:@"Hello"];
    self.myString = tempString;
    [tempString release];
    NSLog(@"%@",myString);
}

-(void)dealloc{
    [myString release];
}
-(void)viewDidUnload{
    [myString release];
    self.myString=nil;
}

I really need an idiot guide for this cause I do not understant it yet. Both works. Also am i using the release in dealloc and viewDidUnload correct?? Thank you in advance

Answer 1

@property and @synthesize provides the getter and setter (accessors) methods rather than you having to write it out yourself. The declaration is made with @property and it is implemented with @synthesize.

So in the main program when you create a new class object (Assuming your class is called MyClass with MyClass.m, MyClass.h), you are able to access your string variable myString using the dot operator. If your object is called NewObject, then you can access the string inside the main program with NewObject.MyString.

You can also use this to set a value for string (i.e. NewObject.MyString = OtherString). Very handy and time-saving. They both work because you are accessing the variables from within the class and so you wouldn’t need to set the accessors.

For the -(void)dealloc you also need [super dealloc] inside there to release the variables of the superclass. You don’t need to release MyString in viewDidUnload as you have done it in the -(void)dealloc method.

When you allocate memory in -(void)viewDidLoad, then you would need to release it in -(void)viewDidUnload, but you haven’t here so it isn’t needed.