Each class has almost one method named addObserver

[imgVURL addObserver:<#(NSObject *)observer#> forKeyPath:<#(NSString *)keyPath#> options:<#(NSKeyValueObservingOptions)options#> context:<#(void *)context#>]

Here, imgVURL is an image which is going to be load an image asynchronously. When image will be loaded dynamically - other class will set an image from loaded data.

• Now, my question is how can we add an observer to UIImageView's instance.
• Observer and notifications are same or not ?
• If it is not then what's different ?

Let's have some sample code That I did in my project to understand my question.

// locating image view from Scroll view by it's tag
imgVURL=(UIImageView*)[scrMain viewWithTag:(kTagImagesTag+i)];
// ImageViewURL is a class which contains methods of 
// didReceiveResponse
// didReceiveData
// connection
ImageViewURL *tmp=[[ImageViewURL alloc] init];
// it has a nonatomic property which will take the reference of my image view
tmp.imgV=imgVURL;
// now I will pass a url from my an array to property strURL
// in strUrl I have custom setter 
// in which I am initializing a connection 
tmp.strUrl=[NSURL URLWithString:[[tblmain objectAtIndex:i] valueForKey:@"url"]];


// from ImageViewURL.m file
-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
    // NSLog@"ImageView Ref From - %@",imgV);
    // see imgV has reference of my -> imgVURL (nonatomic,assign) 
    imgV.image=[UIImage imageWithData:myWebData];
    [connection release]; connection=nil;
}
// as you can see in above code many many images are loaded asynchronously 
// now How can I add an observer to an imageview whether it received or not.