runtime 实现序列化

• (void)encodeWithCoder:(NSCoder *)aCoder {

  while (cls != NSObject.class) {
      //判断是本身类还是父类
      BOOL isSelfClass = NO;
      if (cls == self.class) {
          isSelfClass = YES;
      }
      
      unsigned int ivarCount = 0;
      unsigned int propVarCount = 0;
      unsigned int sharedVarCount = 0;
      //变量列表，含属性以及私有变量
      Ivar *lvarList = isSelfClass ? class_copyIvarList(cls, &ivarCount):NULL;
      objc_property_t *proplist = isSelfClass ? NULL:class_copyPropertyList(cls, &propVarCount);
      sharedVarCount = isSelfClass ? ivarCount:propVarCount;
      
      for (int i = 0; i < sharedVarCount; i++) {
          const char *varname = isSelfClass ? ivar_getName(*(lvarList + i)) : property_getName(*(proplist + i));
          NSString *key = [NSString stringWithUTF8String:varname];
          id value = [self valueForKey:key];
          NSArray *filters = @[@"superclass",@"description",@"debugDescription",@"hash"];
          if (value && [filters containsObject:key] == NO) {
              [aCoder encodeObject:value forKey:key];
          }
      }
      
      free(lvarList);
      free(proplist);
      cls = class_getSuperclass(cls);//指向父类
  }
  

}

• (instancetype)initWithCoder:(NSCoder *)aDecoder {

    if (self) {
        Class cls = self.class;
        while (cls != NSObject.class) {
            //判断是本身类还是父类
            BOOL isSelfClass = NO;
            if (cls == self.class) {
                isSelfClass = YES;
            }

            unsigned int ivarCount = 0;
            unsigned int propVarCount = 0;
            unsigned int sharedVarCount = 0;
            //变量列表，含属性以及私有变量
            Ivar *lvarList = isSelfClass ? class_copyIvarList(cls, &ivarCount):NULL;
            objc_property_t *proplist = isSelfClass ? NULL:class_copyPropertyList(cls, &propVarCount);
            sharedVarCount = isSelfClass ? ivarCount:propVarCount;

            for (int i = 0; i < sharedVarCount; i++) {
                const char *varname = isSelfClass ? ivar_getName(*(lvarList + i)) : property_getName(*(proplist + i));
                NSString *key = [NSString stringWithUTF8String:varname];
                id value = [aDecoder decodeObjectForKey:key];
                NSArray *filters = @[@"superclass",@"description",@"debugDescription",@"hash"];
                if (value && [filters containsObject:key] == NO) {
                    [self setValue:value forKey:key];
                }
            }

            free(lvarList);
            free(proplist);
            cls = class_getSuperclass(cls);//指向父类
        }
    }
    return self;
}