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. The observer must implement the key-value observing method observeValue(forKeyPath:of:change:context:).

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

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.

See Also

Key-Value Observing

func addObserver(NSObject, toObjectsAt: IndexSet, forKeyPath: String, options: NSKeyValueObservingOptions = [], context: UnsafeMutableRawPointer?)

Registers an observer to receive key value observer notifications for the specified key-path relative to the objects at the indexes.

func removeObserver(NSObject, fromObjectsAt: IndexSet, forKeyPath: String)

Removes anObserver from all key value observer notifications associated with the specified keyPath relative to the array’s objects at indexes.