The difference between @private, @protected and @public

The difference between @private, @protected and @public

Diagram between classes

@private can only be used in declared classes, and its subclasses are not able to use instance variables declared with @private

@protected can only be used in declared classes, but its subclasses have the qualification to declare variables using @protected

@public can be used globally, a property that has a global property

The instance variable actually supports KVO, if you write the Setter,getter method for the instance variable

related source

#import <UIKit/UIKit.h>@interface  titleview:uiview {@private     int        _count;    // can only be used    in the current class @protected     nsstring  *_title;    // the current class and subclass can use the    @public     nsstring  //  can be used anywhere } @property (Nonatomic, Strong) NSString   *info; @end

#import "TitleView.h"@implementationTitleview-(Instancetype) initWithFrame: (CGRect) frame { self=[Super Initwithframe:frame]; if(self) {_count=4; _title=@"Title"; _subtitle=@"SubTitle"; }        returnSelf ;}@end

#import " TitleView.h " // Moretitleview inherited from Titleview @interface Moretitleview:titleview @end

#import " MoreTitleView.h " @implementation Moretitleview- (Instancetype) initWithFrame: (CGRect) Frame {        = [Super Initwithframe:frame] ;     if (self) {            }        return to self ;} @end

Instant no write Setter,getter method, but also can use Kvo oh, just need to manually trigger the

The difference between @private, @protected and @public