macOS Replacing an item in an ArrayController

[SimonKravis]

I am modifying an Objective C application which displays members of set of images shown in an NSTableView control which obtains data from an ArrayController. I would like to replace one of the images in the array control. I have tried to do this by first removing the item, using the RemoveObject method and then adding the replacement at the original image location using the method

 - (void)insertObject:(id)object atArrangedObjectIndex:(NSUInteger)index;

. However, when I do this I get the error

addObserver:forKeyPathptions:context:] is not supported.