Returns a Boolean value that indicates whether the observed object supports automatic key-value observation for the given key.
- iOS 2.0+
- macOS 10.3+
- tvOS 9.0+
- watchOS 2.0+
true if the key-value observing machinery should automatically invoke
did whenever instances of the class receive key-value coding messages for the
key, or mutating key-value-coding-compliant methods for the
key are invoked; otherwise
The default implementation returns
true. Starting in OS X 10.5, the default implementation of this method searches the receiving class for a method whose name matches the pattern
+automatically, and returns the result of invoking that method if it is found. Any found methods must return
BOOL. If no such method is found
true is returned.