Understanding EAGLView

I am going through the EAGLView files from the apple iphone sample code and I am trying to understand how the EAGLViewDelegate protocol works.

Question:

How is this function called didResizeEAGLSurfaceForView

? I don't see an implementation?

EAGLView.h

@protocol EAGLViewDelegate <NSObject>
- (void) didResizeEAGLSurfaceForView:(EAGLView*)view; 
   //Called whenever the EAGL surface has been resized
@end

@interface EAGLView : UIView
{
  @private
    id<EAGLViewDelegate>    _delegate;
}


@property(assign) id<EAGLViewDelegate> delegate;

      

        
        
        
      

    

EAGLView.m

@implementation EAGLView

@synthesize 
    delegate      = _delegate, 

//......
@end