Raises an exception.
- iOS 2.0+
- macOS 10.4+
- tvOS 9.0+
- watchOS 2.0+
The object to remove as an observer.
A key-path, relative to the array, for which
observeris registered to receive KVO change notifications. This value must not be
NSArray objects are not observable, so this method raises an exception when invoked on an
NSArray object. Instead of observing an array, observe the to-many relationship for which the array is the collection of related objects.