OC Base Note-The visibility of member variables (Guangzhou Black horse Phase I)

@private: Private, only the object method in this class can access it directly
A member variable is defined in that class to be used in that class
@protected: Protected: Can only be accessed directly in this class and subclass, no longer externally accessible

@public: Public, everyone can use, in this class, sub-class, external can be accessed

@package: Mainly used within the framework, within the framework equivalent to @protected, outside the frame equivalent to @private (understand)

This class: A class that defines this member variable
Modifier that controls visibility, from the start of use until all member variables end or encounter other control visibility modifiers

The member variable can also be defined within the implementation file, but the member variable is private, and it is private regardless of the visibility modifier used.

OC Base Note-The visibility of member variables (Guangzhou Black horse Phase I)