OC基础 类别

@interface integer : NSObject
@property int integer;
@end

@implementation integer

@end

#import <Cocoa/Cocoa.h>
#import "integer.h"
NS_ASSUME_NONNULL_BEGIN
// 类别 没有成员变量

@interface integer(display) //原有类名（类别名）

-(void)show;
-(void)add:(integer*)other;
-(void)sub:(integer*)other;
-(void)mul:(integer*)other;
-(void)div:(integer*)other;
@end

#import "integer+display.h"

@implementation integer(display)
-(void)show
{
    
    
//    NSLog(@"hello world");
    NSLog(@"%i",self.integer);
}
    
-(void)add:(integer*)other
    {
        self.integer+=other.integer;
        
    }

-(void)sub:(integer*)other
{
    
    self.integer-=other.integer;
    
}
-(void)mul:(integer*)other
{
    self.integer*=other.integer;
}
-(void)div:(integer*)other
{
    if(other.integer!=0)
    {
        
        self.integer/=other.integer;
        
    }
    
}
@end