一、Class
在之前的文章中我们提到，所有的对象都有个isa指针指向它对应的类Class，而Class是一个objc_class结构体，结构体中：
- 实例变量列表objc_ivar_list
- 方法列表objc_method_list
对应的runtime获取方法：
Ivar *class_copyIvarList(Class cls, unsigned int *outCount)
Method *class_copyMethodList(Class cls, unsigned int *outCount)
首先我们先创建一个Test类：
//
// Test.h
// RuntimeKVC
//
// Created by z on 2019/5/24.
// Copyright © 2019年 com.jzsec. All rights reserved.
//
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface Test : NSObject
{
@public
NSString *name;
/* 头文件中定义私有变量，默认为@protected */
@private
NSString *major;
}
@property (nonatomic, strong) Test *childTest;
@end
NS_ASSUME_NONNULL_END
//
// Test.m
// RuntimeKVC
//
// Created by z on 2019/5/24.
// Copyright © 2019年 com.jzsec. All rights reserved.
//
#import "Test.h"
@interface Test ()
{
/* 类扩展区域定义私有变量，默认j就是@private */
int age;
}
/* 类扩展区域定义私有属性 */
@property (nonatomic, copy) NSString *job;
/* 类扩展区域定义私有变量，默认j就是@private */
- (void)test;
@end
@implementation Test
-(void)test
{
NSLog(@"这是个私有实例方法");
}
@end
二、Runtime访问
runtime暴力访问私有属性、私有变量和私有方法
//获取实例变量列表
unsigned int count = 0;
Ivar *members = class_copyIvarList([Test class], &count);
//打印所有的变量名及其类型 访问私有属性和变量
for (int i=0; i<count; i++)
{
Ivar var = members[i];
const char *memberName = ivar_getName(var);
const char *memberType = ivar_getTypeEncoding(var);
NSLog(@"name:%s type:%s", memberName, memberType);
NSString *varName = [NSString stringWithUTF8String:memberName];
if ([varName isEqualToString:@"name"])
{
object_setIvar(test, var, @"老王");
NSString *name = object_getIvar(test, var);
NSLog(@"name=%@", name);
}
else if ([varName isEqualToString:@"major"])
{
object_setIvar(test, var, @"计算机");
NSString *major = object_getIvar(test, var);
NSLog(@"major=%@", major);
}
else if ([varName isEqualToString:@"age"])
{
object_setIvar(test, var, @(30));
int age = [object_getIvar(test, var) intValue];
NSLog(@"age=%d", age);
}
else if ([varName isEqualToString:@"_job"])
{
object_setIvar(test, var, @"工程师");
NSString *job = object_getIvar(test, var);
NSLog(@"job=%@", job);
}
}
/* 暴力访问私有方法 */
//获取类对象方法列表
unsigned int countM = 0;
Method *methods = class_copyMethodList([Test class], &countM);
for (int i=0; i<countM; i++)
{
//获取方法名
SEL sel = method_getName(methods[i]);
NSString *selName = NSStringFromSelector(sel);
NSLog(@"method:%@",selName);
if (selName && [selName isEqualToString:@"test"])
{
//执行该方法
[test performSelector:sel];
}
}
打印结果：
2019-08-08 18:01:44.593507+0800 RuntimeKVC[23807:412395] name:name type:@"NSString"
2019-08-08 18:01:44.593616+0800 RuntimeKVC[23807:412395] name=老王
2019-08-08 18:01:44.593635+0800 RuntimeKVC[23807:412395] name:major type:@"NSString"
2019-08-08 18:01:44.593676+0800 RuntimeKVC[23807:412395] major=计算机
2019-08-08 18:01:44.593691+0800 RuntimeKVC[23807:412395] name:age type:i
2019-08-08 18:01:44.593745+0800 RuntimeKVC[23807:412395] age=30
2019-08-08 18:01:44.593761+0800 RuntimeKVC[23807:412395] name:_childTest type:@"Test"
2019-08-08 18:01:44.593784+0800 RuntimeKVC[23807:412395] name:_job type:@"NSString"
2019-08-08 18:01:44.593803+0800 RuntimeKVC[23807:412395] job=工程师
2019-08-08 18:01:44.593884+0800 RuntimeKVC[23807:412395] method:newProperty
2019-08-08 18:01:44.593961+0800 RuntimeKVC[23807:412395] method:setNewProperty:
2019-08-08 18:01:44.593990+0800 RuntimeKVC[23807:412395] method:setChildTest:
2019-08-08 18:01:44.594044+0800 RuntimeKVC[23807:412395] method:childTest
2019-08-08 18:01:44.594087+0800 RuntimeKVC[23807:412395] method:test
2019-08-08 18:01:44.605142+0800 RuntimeKVC[23807:412395] 这是个私有实例方法
2019-08-08 18:01:44.605186+0800 RuntimeKVC[23807:412395] method:.cxx_destruct
2019-08-08 18:01:44.605276+0800 RuntimeKVC[23807:412395] method:job
2019-08-08 18:01:44.605300+0800 RuntimeKVC[23807:412395] method:setJob:
三、KVO访问
在系统的类目中NSObject(NSKeyValueCoding)，通过这两个方法，就可以用key来读取和设置属性的值：
- (void)setValue:(nullable id)value forKey:(NSString *)key;
- (nullable id)valueForKey:(NSString *)key;
//nullable作用:表示可以为空；nonnull作用:不能为空
在通过key查找对应的属性或变量时：
- 先查找对象的类中是否存在与key对应的访问器方法；
- 查找与key名称相同并且带“_”前缀的成员变量；
- 与key名称相同的属性；
- 以上都没有，则调用setValue:forUndefinedKey:方法。
/* KVO暴力访问私有属性和私有变量 */
[test setValue:@"testName" forKey:@"name"];
NSString *tname = [test valueForKey:@"name"];
[test setValue:@"18" forKey:@"age"];
NSString *tage = [test valueForKey:@"age"];
[test setValue:@"mathmetics" forKey:@"major"];
NSString *tmajor = [test valueForKey:@"major"];
NSLog(@"name:%@ age:%@ major:%@", tname, tage, tmajor);
Test *child = [Test new];
test.childTest = child;
child->name = @"晨光";
NSString *cname = [test valueForKeyPath:@"childTest.name"];
NSLog(@"test.childTest.name:%@", cname);
[test setValue:@"傻×" forKeyPath:@"childTest.name"];
NSString *cname1 = [test valueForKeyPath:@"childTest.name"];
NSLog(@"test.childTest.name:%@", cname1);
打印结果：
2019-08-08 18:01:44.605938+0800 RuntimeKVC[23807:412395] name:testName age:18 major:mathmetics
2019-08-08 18:01:44.606054+0800 RuntimeKVC[23807:412395] test.childTest.name:晨光
2019-08-08 18:01:44.606084+0800 RuntimeKVC[23807:412395] test.childTest.name:傻×
