利用runtime归档的好处就在于，不管类的属性有多少个，都不用担心，它都会自动帮你处理好。

首先新建一个Person类：

Person.h

#import <Foundation/Foundation.h>

@interface Person : NSObject<NSCoding>

@property (retain, nonatomic) NSString *name;
@property (assign, nonatomic) int age;

@end

Person.m

#import "Person.h"
#import <objc/runtime.h>

@implementation Person

// 当外边归档这个对象的时候，就会调用这个方法，如果不实现就会报警！！
-(void)encodeWithCoder:(NSCoder *)aCoder {
    unsigned int outCount = 0;
    Ivar *ivars = class_copyIvarList([self class], &outCount);
    for (unsigned int i = 0; i < outCount; i++)
    {
        // 取出成员变量
        Ivar ivar = ivars[i];
        const char *name = ivar_getName(ivar);
        // 通过Ivar拿到key
        NSString *key = [NSString stringWithUTF8String:name];
        // 通过KVC获得属性的值
        id value = [self valueForKey:key];
        [aCoder encodeObject:value forKey:key];
    }
    // 在C语言里，但凡看到New,Creat,Copy，都要释放指针
    free(ivars);
}

// 解档时调用
-(instancetype)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    if (self) {
        // 解档
        unsigned int outCount = 0;
        Ivar *ivars = class_copyIvarList([self class], &outCount);
        for (unsigned int i = 0; i < outCount; i++)
        {
            Ivar ivar = ivars[i];
            const char *name = ivar_getName(ivar);
            NSString *key = [NSString stringWithUTF8String:name];
            // 解档
            id value = [aDecoder decodeObjectForKey:key];
            // 利用KVC设置
            [self setValue:value forKey:key];
        }
        free(ivars);
    }
    return self;
}
@end

在控制器中调用

存的方法

// 存
- (IBAction)save:(id)sender {
    Person *p = [[Person alloc] init];
    p.name = @"henry";
    p.age  = 18;
    
    NSString *temp = NSTemporaryDirectory();
    NSString *fileTemp = [temp stringByAppendingString:@"henry.henry"];
    
    // 归档
    [NSKeyedArchiver archiveRootObject:p toFile:fileTemp];
}

读的方法

// 读
- (IBAction)read:(id)sender {
    NSString *temp = NSTemporaryDirectory();
    NSString *fileTemp = [temp stringByAppendingString:@"henry.henry"];
    
    Person *p = [NSKeyedUnarchiver unarchiveObjectWithFile:fileTemp];
    NSLog(@"name=%@,age=%d",p.name,p.age);
}