Header file declaration in iPhone

What is the difference between them:-

Approach 1:-

@interface EffortView : UIView {

}    
@property (nonatomic, retain) UIView *homeV开发者_如何学Pythoniew;    
@end

Approach 2:-

@interface EffortView : UIView {
    UIView *homeView;
}    
@property (nonatomic, retain) UIView *homeView;    
@end

I have synthesized the properties in both cases. Both of them works. I am using Xcode 4.0 on Mac 10.6.6

Please enlighten me.

Thank you All.

The first approach won't work on 32-bit Mac OS X runtimes because each property must have a corresponding instance variable. 64-bit and iOS runtimes automatically create the instance variable for you, so in that case, it is enough to use the second approach.

The bottom line is: if you are 100% sure that you won't ever target 32-bit Mac OS X systems and none of the components of your software will ever be used on that platform, you can safely omit the instance variables.