Objective-C inheritance

1. Inheritance mainly reflects the relationship between classes. Using inheritance can reduce repeatedCode.

 

2. Inheritance Mechanism Method lookup: If a message is sent to an object, the schedulingProgramFind the method corresponding to the message in this object. If the Scheduler cannot find the object, it will go to the super class to find it. If no more information is found, follow the inheritance chain to find the corresponding method of the message. If not found, a compile-time warning and a running error will appear.

 

3. The objective-C instance variable corresponds to the data member of C. The instance variables of the class and the code are stored in different locations. Therefore, if there is a hidden parameter self pointing to the instance variables.