利用运行时实现归档、解档，并将其封装成宏

• 继承 NSObject 并遵守 NSCoding 协议，创建一个类

#import <Foundation/Foundation.h>
@interface Person : NSObject<NSCoding>
@property(nonatomic, copy) NSString *name;
@property(nonatomic, assign) NSInteger age;
@end

• 在 .m 中 NSCoding 协议的方法，需要引入运行时头文件 #import <objc/runtime.h>

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

@implementation Person
- (void)encodeWithCoder:(NSCoder *)encoder{
    unsigned int count = 0;
    Ivar * ivars = class_copyIvarList([Person class], &count);

    for (int i = 0; i < count; i++) {
        // 取出i位置对应的成员变量
        Ivar ivar = ivars[i];
        // 查看成员变量
        const char * name = ivar_getName(ivar);
        // 归档
        NSString * key = [NSString stringWithUTF8String:name];
        id value = [self valueForKey:key];
        [encoder encodeObject:value forKey:key];
    }
    // 释放内存
    free(ivars);
}

- (instancetype)initWithCoder:(NSCoder *)decoder{
    if (self = [super init]) {
        unsigned int count = 0;
        Ivar * ivars = class_copyIvarList([Person class], &count);

        for (int i = 0; i < count; i++) {
            // 取出i位置对应的成员变量
            Ivar ivar = ivars[i];
            // 查看成员变量
            const char * name = ivar_getName(ivar);
            // 解档
            NSString * key = [NSString stringWithUTF8String:name];
            id value = [decoder decodeObjectForKey:key];
            // 设置到成员变量身上
            [self setValue:value forKey:key];
        }
        // 释放内存
        free(ivars);
    }
    return self;
}
@end

• 归档解档测试

- (void)viewDidLoad {
    [super viewDidLoad];
    
    Person * p = [[Person alloc] init];
    p.name = @"Tom";
    p.age = 28;
    
    // 归档路径
    NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    
    NSString * filePath = [path stringByAppendingPathComponent:@"archiver_person"];
    
    // 归档
    BOOL result = [NSKeyedArchiver archiveRootObject:p toFile:filePath];
    
    if (result) {
        NSLog(@"归档成功");
    }else{
        NSLog(@"归档失败");
    }
    
    // 解档
    Person * p1 = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];
    NSLog(@"%@", p1.name);
}

• 新建头文件 Archiver.h， 将 Person.m 中 NSCoding 协议的方法写成宏，以便于多处调用，而不需重相同的工作，代码如下：

#define ArchiverM(className)\
- (void)encodeWithCoder:(NSCoder *)encoder{\
    unsigned int count = 0;\
    Ivar * ivars = class_copyIvarList([className class], &count);\
    for (int i = 0; i < count; i++) {\
        Ivar ivar = ivars[i];\
        const char * name = ivar_getName(ivar);\
        NSString * key = [NSString stringWithUTF8String:name];\
        id value = [self valueForKey:key];\
        [encoder encodeObject:value forKey:key];\
    }\
    free(ivars);\
}\
- (instancetype)initWithCoder:(NSCoder *)decoder{\
    if (self = [super init]) {\
        unsigned int count = 0;\
        Ivar * ivars = class_copyIvarList([className class], &count);\
        for (int i = 0; i < count; i++) {\
            Ivar ivar = ivars[i];\
            const char * name = ivar_getName(ivar);\
            NSString * key = [NSString stringWithUTF8String:name];\
            id value = [decoder decodeObjectForKey:key];\
            [self setValue:value forKey:key];\
        }\
        free(ivars);\
    }\
    return self;\
}

• 宏的使用,在需要归/解档的类的 .m文件中引入 #import "Archiver.h",并调用宏 ArchiverM(类名)

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

@implementation Person

ArchiverM(Person)

//- (void)encodeWithCoder:(NSCoder *)encoder{
//    unsigned int count = 0;
//    Ivar * ivars = class_copyIvarList([Person class], &count);
//
//    for (int i = 0; i < count; i++) {
//        // 取出i位置对应的成员变量
//        Ivar ivar = ivars[i];
//        // 查看成员变量
//        const char * name = ivar_getName(ivar);
//        // 归档
//        NSString * key = [NSString stringWithUTF8String:name];
//        id value = [self valueForKey:key];
//        [encoder encodeObject:value forKey:key];
//    }
//    free(ivars);
//}
//
//- (instancetype)initWithCoder:(NSCoder *)decoder{
//    if (self = [super init]) {
//        unsigned int count = 0;
//        Ivar * ivars = class_copyIvarList([Person class], &count);
//
//        for (int i = 0; i < count; i++) {
//            // 取出i位置对应的成员变量
//            Ivar ivar = ivars[i];
//            // 查看成员变量
//            const char * name = ivar_getName(ivar);
//            // 解档
//            NSString * key = [NSString stringWithUTF8String:name];
//            id value = [decoder decodeObjectForKey:key];
//            // 设置到成员变量身上
//            [self setValue:value forKey:key];
//        }
//        free(ivars);
//    }
//    return self;
//}
@end

示例代码