通常情况下，我们用
【类别】去对【原有类】进行【属性】的添加，如果在编译的时候不会报错，但是在运行阶段则会崩溃！
所以，我们通过对属性的set、get方法重写并调用【关联属性】的方法，即可完成属性的【赋值 和 打印】，并且不会崩溃。
static const char delegateKey //这是用来确认唯一身份的标识🆔
■ 设置类关联属性
objc_setAssociatedObject (object , key , value , policy)■ 获取类关联属性
objc_getAssociatedObject (object , key)
object：被关联的对象（那个对象需要关联）
key：map表里key的一个唯一区分标志
value：属性
policy：属性以什么方式去保存（copy、strong、assign、retain等）
image.png
student.h
#import <Foundation/Foundation.h>
@interface CFStudent : NSObject
@property(nonatomic,copy)NSString *name;
//吃东西
- (void)eating;
@end
student.m
#import "CFStudent.h"
#import "CFStudent+Extension.h"
/*
*扩展（私有：变量、属性）
*/
@interface CFStudent()
{
NSInteger _num; //学号
}
@property(nonatomic,assign)BOOL sex;
@end
@implementation CFStudent
//吃东西
- (void)eating
{
_num = 123456;
self.sex = YES;
_class = @(2018);
NSLog(@"_num:%ld self.sex:%d _class:%@",(long)_num,self.sex,_class);
NSLog(@"Person eating！");
}
@end
CFStudent+Category.h
#import "CFStudent.h"
@protocol ExaminationRul
@optional
- (void)level6test;
@end
/*
*分类（实例属性、类属性、实例方法、类方法、）
*/
@interface CFStudent (Category)<ExaminationRul>
//注意：这些属性都使用不了，因为分类不能生成变量（内存已分配好），所以也没有setter、getter方法
@property(nonatomic,copy)NSString *age;
@property(class,nonatomic,copy)NSString *teacher; //类属性使多个实例可以共享变量
@property(nonatomic,weak)id <ExaminationRul> delegate;
//玩耍
- (void)playing;
//睡觉
+ (void)sleeping;
@end
CFStudent+Category.m
#import "CFStudent+Category.h"
#import <objc/runtime.h>
@implementation CFStudent (Category)
static const char ageKey;
static const char teacherKey;
static const char delegateKey;
- (void)setAge:(NSString *)age
{
objc_setAssociatedObject(self, &ageKey, age, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (NSString *)age
{
NSString *age = objc_getAssociatedObject(self, &ageKey);
return age;
}
+ (void)setTeacher:(NSString *)teacher
{
objc_setAssociatedObject(self, &teacherKey, teacher, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
+ (NSString *)teacher
{
//注意：这里的self是CFStudent
//而实例方法里的self是student
NSString *teacher = objc_getAssociatedObject(self, &teacherKey);
return teacher;
}
- (void)setDelegate:(id<ExaminationRul>)delegate
{
objc_setAssociatedObject(self, &delegateKey, delegate, 0);
}
- (id<ExaminationRul>)delegate
{
id<ExaminationRul> delegate = objc_getAssociatedObject(self, &delegateKey);
return delegate;
}
//玩耍
- (void)playing
{
NSLog(@"Student playing！");
}
//睡觉
+ (void)sleeping
{
NSLog(@"Student sleeping！");
}
- (void)level6test{
NSLog(@"ExaminationRul-level6test！");
}
@end
CFStudent+Extension.h
#import "CFStudent.h"
@interface CFStudent ()
{
NSNumber *_class; //班级
}
@end
.main
#import <Foundation/Foundation.h>
#import "CFStudent.h"
#import "CFStudent+Category.h"
int main(int argc, const char * argv[]) {
@autoreleasepool {
CFStudent *student = [[CFStudent alloc]init];
/*
*1.属性
*/
student.name = @"lilei";
NSLog(@"student.name：%@",student.name);
student.age = @"20";
NSLog(@"student.age：%@",student.age);
CFStudent.teacher = @"zhangsan";
NSLog(@"CFStudent：%@",CFStudent.teacher);
/*
*2.方法
*/
[student eating];
[student playing];
[CFStudent sleeping];
/*
*3.协议
*/
student.delegate = student;
[student.delegate level6test];
}
return 0;
}
打印结果:
2019-03-13 14:10:13.458535+0800 Category Associat的介绍[13462:1406592] student.name：lilei
2019-03-13 14:10:13.458766+0800 Category Associat的介绍[13462:1406592] student.age：20
2019-03-13 14:10:13.458803+0800 Category Associat的介绍[13462:1406592] wdwname:sdf
2019-03-13 14:10:13.458864+0800 Category Associat的介绍[13462:1406592] CFStudent：zhangsan
2019-03-13 14:10:13.458917+0800 Category Associat的介绍[13462:1406592] _num:123456 self.sex:1 _class:2018
2019-03-13 14:10:13.458945+0800 Category Associat的介绍[13462:1406592] Person eating！
2019-03-13 14:10:13.458961+0800 Category Associat的介绍[13462:1406592] Student playing！
2019-03-13 14:10:13.458979+0800 Category Associat的介绍[13462:1406592] Student sleeping！
2019-03-13 14:10:13.458998+0800 Category Associat的介绍[13462:1406592] ExaminationRul-level6test！
Program ended with exit code: 0
