性能完善，使用简单。

图1 - 效果示例

过程：

• 1. 建立一个模型，一般即为你要存储数据的模型，我这里是用户数据。
     ~1.1 模型的数据类型，模型要遵守<NSCoding>
     @property(nonatomic, copy)NSString *userName;
     @property(nonatomic, copy)NSString *userPhone;
     @property(nonatomic, assign)NSInteger userAge;
     + (SJUserModel *)userWithName:(NSString *)name age:(NSInteger)age phone:(NSString *)phone;
     ~1.2 实现模型赋值方法
     + (SJUserModel *)userWithName:(NSString *)name age:(NSInteger)age phone:(NSString *)phone
     {
     SJUserModel *model = [[self alloc] init];
     model.userName = name;
     model.userAge = age;
     model.userPhone = phone;
     return model;
     }
     ~1.3 实现归档自动触发 和 解归档自动触发方法
     - (void)encodeWithCoder:(NSCoder *)aCoder{
     //保存值
     [aCoder encodeObject:self.userName forKey:@"userName"];
     [aCoder encodeObject:self.userPhone forKey:@"userPhone"];
     [aCoder encodeInteger:self.userAge forKey:@"userAge"];
     }

     - (instancetype)initWithCoder:(NSCoder *)aDecoder{
       if (self = [super init]) {
        //取值
        self.userName = [aDecoder decodeObjectForKey:@"userName"];
        self.userPhone = [aDecoder decodeObjectForKey:@"userPhone"];
        self.userAge = [aDecoder decodeIntegerForKey:@"userAge"];
        }
     return self;
     }
     

• 2.建立归档类
  ~2.1 声明外部接口方法
  /用户信息归档/
  + (void)archiverUserInfo:(SJUserModel )model;
  /用户信息读档/
  + (SJUserModel )currentArchiverUserInfo;
  ~2.2 具体实现归档、解归档部分
  /归档/
  + (void)archiverUserInfo:(SJUserModel )model{
  [self archiverModel:model fileName:kUserInfoFileName dataName:kUserInfoDataKey];
  }
  /解归档/
  +(SJUserModel )currentArchiverUserInfo{
  //如果内存中有UserModel,直接读取，否则去磁盘读取
  if ([self memoryUserInfo] != nil) {
  return [self memoryUserInfo];
  }
  return [self unArchiverWithFieldName:kUserInfoFileName dataName:kUserInfoDataKey];
  }
  /获取当前内存中的用户信息/
  + (SJUserModel )memoryUserInfo{
  AppDelegate delegate = [UIApplication sharedApplication].delegate;
  return delegate.currentUserModel;
  }
  /路径/
  + (NSString *)filePathComponentName:(NSString *)fileName{
  return [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0] stringByAppendingPathComponent:fileName];
  }
  + (void)archiverModel:(NSObject *)model fileName:(NSString *)fileName dataName:(NSString *)dataName{
  NSString *dataFilePath = [self filePathComponentName:fileName];
  NSMutableData *data = [[NSMutableData alloc] init];
  NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];

    [archiver encodeObject:model forKey:dataName];
    [archiver finishEncoding];
    [data writeToFile:dataFilePath atomically:YES];
  }
  
  + (id)unArchiverWithFieldName:(NSString *)fileName dataName:(NSString *)dataName{
    NSString *filePath = [self filePathComponentName:fileName];
    NSData *data = [[NSMutableData alloc] initWithContentsOfFile:filePath];
    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    id model = [unarchiver decodeObjectForKey:dataName];
    [unarchiver finishDecoding];
    if (model == nil) {
    NSLog(@"读档信息为空");
    }
    return model;
  }
  

• 3.至此，封装完毕。使用部分
  ~3.1 登录时给模型赋值，归档模型数据
  <pre>SJUserModel *userModel = [SJUserModel userWithName:self.nameTF.text age:self.ageTF.text.integerValue phone:self.phoneTF.text];
  [SJArchive archiverUserInfo:userModel];</pre>~3.2下一次进APP时从内存中或者磁盘解归档数据
  <pre>SJUserModel *model = [SJArchive currentArchiverUserInfo];
  self.nameLB.text = model.userName;
  self.ageLB.text = [NSString stringWithFormat:@"%ld",model.userAge];
  if ([self.ageLB.text isEqualToString:@"0"])
  self.ageLB.text = @"";
  }
  self.phoneLB.text = model.userPhone;</pre>
  ~3.2退出登录时，给当前用户数据模型置"空"，然后归档一次"空"模型
  <pre>SJUserModel *model = [SJArchive currentArchiverUserInfo];
  model.userName = @"";
  model.userPhone = @"";
  model.userAge = @"".integerValue;
  //归档
  [SJArchive archiverUserInfo:model];</pre>

希望本文会对看到的同学有帮助，原文代码参考：https://github.com/SPIREJ/SJArchiveDemo