Use this attribute to make an Objective-C interface method optional.
An optional method is a method that does **not** have to be implemented in
the class that implements the interface. To safely call an optional method,
a runtime check should be performed to make sure the receiver implements the
method.
Use this attribute to make an Objective-C interface method optional.
An optional method is a method that does **not** have to be implemented in the class that implements the interface. To safely call an optional method, a runtime check should be performed to make sure the receiver implements the method.