CODEWITHSUNDEEP
iosobjective-ciphone
cijianzy
cijianzy

Reputation: 71

What is different between the two ways to define the Private member variable

The first way.

//Myclass.m
@implementation Myclass{
    NSString * name;
}
-(void) print{
    NSLog(@"%@",name);
}
@end

The second way.

//Myclass.m
@interface Myclass()
@property(nonatomic) NSString *name;
@end

@implementation Myclass
-(void) print{

    NSLog(@"%@",_name);
}
@end

Why can't to access 'name' by 'self.name' in the first way but can use 'self.name' and '_name' in the second way. What is different between the two ways.

I confused by this because i want override the 'isEqual' method , the first way can't access the other object's private member variable but the second way can use '.' to access.

Forgive my English.

Upvotes: 0

Views: 36

Answers (2)

sloik
sloik

Reputation: 732

When compiler will see a @property it will generate a setter and a getter (depending on annotations added to the property). So in the first example compiler adds two methods:

- (void)setName:(NSString *)name {
...
}

- (NSString *)name {
...
}

So you can call a method called 'name' in the first example because it exists ;) In the second case you would have to write them your self. Because this kind of methods are so boiler plate the @property syntax was added so the programer would not have to write basically the same code for any other variable he/she want's to use :)

Upvotes: 1

Fogmeister
Fogmeister

Reputation: 77641

I would use neither of these. I'd always just use the property...

//Myclass.m
@interface Myclass()
@property(nonatomic) NSString *name;
@end

@implementation Myclass

-(void) print{
    NSLog(@"%@",_name);
    NSLog(@"%@",self.name);
}

@end

Properties are synthesised into iVars with getter and setter methods. The iVar is always called _propertyName.

Using a property allows you to fine tune the ARC properties of that more easily than with iVars (IMO anyway).

Upvotes: 1

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