viewController.m文件的调用

#import "ViewController.h"
#import "Person.h"
@interface ViewController ()
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self encodeObject];
    [self decodeObject];
}
- (void)encodeObject{
    Person *myPerson = [[Person alloc] init];
    myPerson.name = @"yjh";
    myPerson.age = 25;
    
    NSMutableData *data = [NSMutableData data];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    [archiver encodeObject:myPerson forKey:@"person"];
    [archiver finishEncoding];
    
    [data writeToFile:[self filePath] atomically:YES];
}
- (void)decodeObject{
    NSData *dataC = [NSData dataWithContentsOfFile:[self filePath]];
    
    NSKeyedUnarchiver *unArch =[[NSKeyedUnarchiver alloc] initForReadingWithData:dataC];
    Person *unPerson = [unArch decodeObjectForKey:@"person"];
    [unArch finishDecoding];
    NSLog(@"dasdf%@",unPerson.name);
}

- (NSString *)filePath{
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString* filePath = [path stringByAppendingPathComponent:@"person.data"];
    return filePath;
}

person.h 文件

#import <Foundation/Foundation.h>

@interface Person : NSObject<NSCoding>
@property (nonatomic, strong) NSString *name;
@property (nonatomic, assign) int age;
@property (nonatomic, strong) NSString *weight;

@end

person.m文件

#import "Person.h"
#import <objc/message.h>
@implementation Person
- (void)encodeWithCoder:(NSCoder *)aCoder{
    
    // runtime方法
    unsigned int count = 0; // 等下要把他的传地址进去
    Ivar *ivars = class_copyIvarList([self class], &count); // 得到成员变量的指针 和 count的值
    
    for (int i = 0; i < count; i++) {
        const char * ivarName = ivar_getName(ivars[i]); // 得到成员变量的名称
        NSString *ivar = [NSString stringWithUTF8String:ivarName]; // C语言的转换成OC的NSString
        id value = [self valueForKey:ivar]; // kvc得到成员变量的值
        [aCoder encodeObject:value forKey:ivar];
    }
    free(ivars); // 释放C语言的内存空间
    
    // 原来方法
//    [aCoder encodeObject:_name forKey:@"name"];
//    [aCoder encodeInt:_age forKey:@"age"];

}
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder{
    // runtime方法
    if (self = [super init]) {
        unsigned int count = 0;
        //获取类中所有成员变量名
        Ivar *ivar = class_copyIvarList([self class], &count);
        for (int i = 0; i<count; i++) {
            Ivar iva = ivar[i];
            const char *name = ivar_getName(iva);
            NSString *strName = [NSString stringWithUTF8String:name];
            //进行解档取值
            id value = [aDecoder decodeObjectForKey:strName];
            //利用KVC对属性赋值
            [self setValue:value forKey:strName];
        }
        free(ivar);
        // 原来方法
//        _name = [aDecoder decodeObjectForKey:@"name"];
//        _age = [aDecoder decodeIntForKey:@"age"];
    }
    return self;
}


@end