Question

I have a bit of a problem in my code, and i’m beginning to wonder if it’s a design issue..

I’m treating my appDelegate class as the primary model for my application. With the appDel class, I have a viewcontroller. In my appdelegate class I store an NSMutableArray called blocks which has all of my block object models. Similarly, in my viewcontroller I have an identical NSMutableArray called blockViews which stores all of my block object views. The way I update the view after receiving notifications from the model is through KVO. In my viewcontroller, I observe each location property of each block in my blocks array (in the app delegate), and update the corresponding blockView in blockViews.

I also have it set up so that whenever I add an object to my blocks array in the appDel, it adds an object to the end of the blockViews’ array. Now, my problem arises when I try to remove an object from my blocks array (in the appDel class). I will not always be removing the last object, and so I am stuck as to how to get the actual index of the object I am trying to remove so that I can remove the corresponding index in my blockViews NSMutableArray.

In my observeValueForKeyPath method, the object being passed is the appDelegate class because I am observing the entire blocks array from my viewcontroller (I implemented the Indexed Array Accessors to allow for KVO notifications to occur), and because of this the object being passed into observeValueForKeyPath is in fact a reference to my appDelegateClass (which makes sense).

But, from this, I cannot obtain the index of which object was removed from the blocks array. Does anybody have any suggestions as to how I could alter this to provide an index, or a way to get the correct index?

Is there any way to observe an array for additions or removals, AND have the object being passed into my observeValueForKeyPath method be the block that was added/removed itself, instead of the appdelegate class?

Answer 1

Can’t you use indexOfObject... (several variations) to get the index, and then remove it in both arrays? (You realize that NSMutableArray implements all the methods of NSArray, right?)