Instance Method

addObserver(_:forKeyPath:options:context:)

Raises an exception.

Declaration

func addObserver(_ observer: NSObject, forKeyPath keyPath: String, options: NSKeyValueObservingOptions = [], context: UnsafeMutableRawPointer?)

Parameters

observer

The object to register for KVO notifications.

keyPath

The key path, relative to the array, of the property to observe. This value must not be nil.

options

A combination of NSKeyValueObservingOptions values that specifies what is included in observation notifications.

context

Arbitrary data that is passed to observer in observeValue(forKeyPath:of:change:context:).

Discussion

NSOrderedSet objects are not observable, so this method raises an exception when invoked on an NSOrderedSet object. Instead of observing an ordered set, observe the to-many relationship for which the ordered set is the collection of related objects.