Synthesizing iVars from properties?

Question

Can I just check what is happening when you do the following (See below), I am right in thinking that no iVars are created in "INTERFACE" just three properties. In the "IMPLEMENTATION" those three properties are assigned to iVars called _window , _animationTimer & _currentFrame which are created by the @synthesize command?

// INTERFACE
@interface testDelegate : NSObject ... {
}
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, assign) NSTimer *animationTimer;
@property (nonatomic, assign) int currentFrame;
...

.

// IMPLEMENTATION
@implementation testDelegate
@synthesize window = _window;
@synthesize animationTimer = _animationTimer;
@synthesize currentFrame = _currentFrame;
...

Answer 1

Yep, that's how it works. @synthesize can now automatically generate the appropriate instance variables as well as accessors for them. It's a relatively recent development in the language.