Runtime 方法替换 和 动态添加实例方法 结合使用

1 #import <Foundation/Foundation.h>
2 
3 @interface Person : NSObject
4 
5 @end

1 #import "Person.h"
2 
3 @implementation Person
4 
5 @end

1 #import <Foundation/Foundation.h>
2 
3 @interface OtherPerson : NSObject
4 
5 
6 @end

 1 //
 2 //  Created by HEYANG on 16/1/11.
 3 //  Copyright © 2016年 HEYANG. All rights reserved.
 4 //
 5 
 6 #import "OtherPerson.h"
 7 #import <objc/message.h>
 8 
 9 @implementation OtherPerson
10 
11 
12 +(void)load{
13     Class clazz = NSClassFromString(@"Person");
14     
15     //获取替换前的类方法
16     Method instance_eat = 
17         class_getClassMethod(clazz, @selector(resolveInstanceMethod:));
18     //获取替换后的类方法
19     Method instance_notEat = 
20         class_getClassMethod(self, @selector(hy_resolveInstanceMethod:));
21     
22     //然后交换类方法
23     method_exchangeImplementations(instance_eat, instance_notEat);
24     
25     //获取替换前的类方法
26     Method class_eat = 
27         class_getClassMethod(clazz, @selector(resolveClassMethod:));
28     //获取替换后的类方法
29     Method class_notEat = 
30         class_getClassMethod(self, @selector(hy2_resolveClassMethod:));
31     
32     //然后交换类方法
33     method_exchangeImplementations(class_eat, class_notEat);
34     
35 }
36 
37 void eat_1(id self,SEL sel)
38 {
39     NSLog(@"到底吃不吃饭了");
40     NSLog(@"%@ %@",self,NSStringFromSelector(sel));
41 }
42 void eat_2(id self,SEL sel, NSString* str1,NSString* str2)
43 {
44     NSLog(@"到底吃不吃饭了");
45     NSLog(@"%@ %@",self,NSStringFromSelector(sel));
46     NSLog(@"打印两个参数值：%@ and %@",str1,str2);
47 }
48 
49 
50 +(BOOL)hy_resolveInstanceMethod:(SEL)sel{
51     //当sel为实现方法中 有 eat 方法
52     if (sel == NSSelectorFromString(@"eat")) {
53         //就 动态添加eat方法
54         
55         // 第一个参数：给哪个类添加方法
56         // 第二个参数：添加方法的方法编号
57         // 第三个参数：添加方法的函数实现（函数地址）
58         // 第四个参数：函数的类型，(返回值+参数类型) v:void @:对象->self :表示SEL->_cmd
59         class_addMethod(self, sel, (IMP)eat_1, "v@:");
60     }
61     return YES;
62 }
63 +(BOOL)hy2_resolveClassMethod:(SEL)sel{
64     
65     if (sel == NSSelectorFromString(@"eat:with:")) {
66         
67         class_addMethod(objc_getMetaClass("Person"), sel, (IMP)eat_2, "v#:@@");
68     }
69     
70     return YES;
71 }
72 
73 @end

 1 /**
 2  *
 3  *  Swap Method and Dynamic add Method (交换方法和动态添加方法)
 4  *
 5  */
 6  
 7 #import <Foundation/Foundation.h>
 8 
 9 //ignore undeclared warm 忽视未声明的警告
10 #pragma clang diagnostic push
11 #pragma clang diagnostic ignored "-Wundeclared-selector"
12 
13 int main(int argc, const char * argv[]) {
14     @autoreleasepool {
15         //get this Person class 拿到了这个Person类
16         Class clazz = NSClassFromString(@"Person");
17         //get this Person Instance 拿到这个Person实例
18         id person = [[clazz alloc] init];
19         
20         //send message to ‘eat‘ method in Person Class or Person Instance
21         //发送消息给Person类或者Person实例的‘eat’方法 不含参数
22         [person performSelector:@selector(eat) withObject:nil];
23         //发送消息给Person类的‘eat’方法 含两个参数
24         [clazz performSelector:@selector(eat:with:) 
25                         withObject:@"Hello" 
26                         withObject:@"World"];
27     }
28     return 0;
29 }
30 
31 #pragma clang diagnostic pop