Instance Variables

[jonthornham]

I am currently learning about ARC and noticed the following in some of the updated texts I've been reading.

I am used to seeing:

Code: (Objective-C)

@interface myViewController: UIViewController
{
        UIButton *myButton;
}

@property (nonatomic, retain) IBOutlet UIButton *myButton;

@end

@implementation myViewController

@synthesize myButton;

...

@end

I see the new format is:

Code: (Objective-C)

@interface myViewController: UIViewController

@property (weak, nonatomic) IBOutlet UIButton *myButton;

@end

@implementation myViewController

@synthesize myButton;

...

@end

I am assuming that the section:

Code: (Objective-C)

{
        UIButton *myButton;
}

Is recognized by simply typing:

Code: (Objective-C)

@property (weak, nonatomic) IBOutlet UIButton *myButton;

Is this true?  Also, is this technically due to ARC or is it that the compiler in Xcode 4.2 allows for the change?

Finally, I notice in the new addition of the book you add the following to the @implementation section:

{
        int numerator;
        int denominator;
}

However, this is not added to the example I used above and is not in the "Transition to ARC" guide.  Is this because they are not objects or is there another reason they are added in the book.

Take care,

Jon

[jonthornham]

I just found the answer to part of my question.  The reason the declarations for numerator and denominator where in the book was because the variables were not synthesized yet.  The addition of the @porperty and @synthesize calls eliminates the need to declare the instance variables. Pretty cool. 

I still have my second question.  Is this part of ARC, or is it simply that Xcode is smarter?

Take care,

Jon

[happyzhb]

jonthornham, it is not part of ARC. I believe Xcode is just getting smarter.

However, the part that "retain" is changed to "weak" in the brackets ("nonatomic" is unchanged) is because of ARC.

[jonthornham]

Thank you for the reply I appreciate it.

[jcmeyer5]

Okay, so for a follow up... is there any reason we would want to put instance variables (other than properties) in the interface file anymore?  Seems to me that properties takes care of the "public" part of variable declaration (since public variables will pretty much always need setter/getter methods), and that anything else should probably be in the implementation file.

Is there a reason I would want a public iVar that is NOT a property?

Thanks!

Jim