Question

Here’s a (reduced) class declaration from an example on apple’s developer:

@interface myController : UITableViewController {

    NSArray *samples;
}

@property (nonatomic, retain) NSArray *samples

What is the purpose of declaring

{

    NSArray *samples;
}

when you declare it again as a property? If you leave out:

{

    NSArray *samples;
}

you can still use @synthesize in your .m and get a reference to it!

I’m a little confused as to the purpose of the first declaration.

Thanks

Answer 1

Properties are just a handy way to declare accessors to you data. It usually leads to some member variable but not necessarily. And that member var can have different name:

@interface myController : UITableViewController {

    NSArray *mSamples;
}

@property (nonatomic, retain) NSArray *samples
@end

@implementation
@synthesize samples = mSamples;
@end

Or you can use properties without vars at all:

@interface myController : UITableViewController {

}

@property (nonatomic, retain) NSArray *samples
@end

@implementation
   -(NSArray*) samples {
    //you can for example read some array from file and return it
   }

   -(void) setSamples:(NSArray*) arr {
     //write that array to file or whatever you want
    }
@end

With new compiler you can use properties without ivars at all, compiler will generate them for you implicitly.