Why must I define variables twice in the Header file?

Question

Why must I define variables twice in the header file? What differences are there between these variables?

The first definition is here:

@interface MyCont         


        

Answer 1

In modern runtime you do NOT need to declare them twice. Just use:

In you .h

@property (nonatomic) NSInteger selectedIndex;

The part between the {} is the declaration of the iVar. And with your @property you declare getter and setters. In modern runtime if you just use the code above you say basicly the same (your iVar is now _selectedIndex).