OBJECTIVE-C member variable access decoration that is, member variable visibility resolution

In general, OBJECTIVE-C access member variable visibility is the same as C + +, just a few @package. The following is a detailed description:

Example:

 
 
@interface CTPerson : NSObject
{
 @private
    int _age;
 @protected
    NSString *_name;
 @public
    double _height;
 @package
    double _weight;
}
  

@private: Private, it can only be accessed directly in the object method of this class

@protected: protected: can only be accessed directly in this class and subclass and cannot be accessed externally

@public: Public, in this class, sub-class, external can access

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

Add: 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 .

Example:

 
@implementation CTPerson
{
  @public
     int _sex; // The member variable will also be treated as private
}

OBJECTIVE-C member variable access decoration that is, member variable visibility resolution