iOS 数据持久化方式 - 归档 反归档

• 所谓归档:将复杂对象转化为NSData类型数据(复杂-->归档-->NSData--->WriteToFile)
  注意:归档是将对象转化为数据字节,以文件的形式存储在磁盘上,

• 所谓反归档:将NSData类型数据转化为复杂对象(读取文件-->NSData-->反归档--->复杂对象)

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  再说归档之前,先说下iOS的数据持久化方式:
  那么问题来了,什么是数据持久化?

  数据持久化(侠义的理解):仅仅指把域对象永久保存到数据库中,(广义的理解):包括和数据库相关的各种操作
  优点:
  1:数据持久化可以减少访问数据库数据的次数,增加应用程序执行的速度;
  2:代码重用性高,能够完成大部分数据库操作;
  3:低耦合,使持久化不依赖于底层数据库和上层业务逻辑实现,更换数据库时只需要修改配置文件而不用修改代码

那么iOS的数据化持久方式有哪些呢?

1:属性列表(Plist文件),NSUserDefault
2:归档(NSKeyedArchiver)
3:数据库(SQlite,CoreData,FMDB(第三方))

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今天重点说下归档和结档的问题
归档的三种方式:

1:对foundation框架的对象进行归档
2:对自定义的对象进行归档
3:对自定义内容进行归档
注意:归档生成的文件是加密的

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下边举简单的例子分别说下归档的三种方式

#pragma mark---对自定义对象进行归档反归档----- (void)archive{//先创建一个Person类/* 第一:复杂对象所属的类一定要遵循NSCoding协议 第二:实现协议中的方法 - (void)encodeWithCoder:(NSCoder *)aCoder; - (instancetype)initWithCoder:(NSCoder *)aDecoder;//归档(由叫序列化)的步骤//对Person类对象进行归档时执行此方法.并对Person类中想要进行归档的所有属性,进行序列化操作- (void)encodeWithCoder:(NSCoder *)aCoder{    [aCoder encodeObject:_name forKey:@"name"];    [aCoder encodeObject:_gender forKey:@"gender"];    [aCoder encodeObject:_age forKey:@"age"];}//反归档(由叫反序列化)的步骤//对Person类对象进行反归档时执行此方法.并对Person类中想要进行反归档的所有属性,进行反序列化操作- (instancetype)initWithCoder:(NSCoder *)aDecoder{    if (self = [super init]) {        _name = [aDecoder decodeObjectForKey:@"name"];        _gender = [aDecoder decodeObjectForKey:@"gender"];        _age = [aDecoder decodeObjectForKey:@"age"];    }        return self;} */    person *per = [person new];    per.name = @"甲甲";    per.age = @"20";    per.gender = @"女";    //归档    //1:准备路径    NSString *path = NSHomeDirectory();    path = [path stringByAppendingString:@"Singel.plist"];    //2:准备存储数据对象(用可变数组进行接收)    NSMutableData *data = [NSMutableData new];    //3:创建归档对象    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];    //4:开始归档    [archiver encodeObject:per forKey:@"person"];    //5:完成归档    [archiver finishEncoding];    //6:写入文件    BOOL result = [data writeToFile:path atomically:YES];    if (result) {        NSLog(@"归档成功:%@",path);    }    //反归档    //1:获取解档路径    NSData *MyData = [NSData dataWithContentsOfFile:path];    //2:创建反归档对象    NSKeyedUnarchiver  *unarchiver= [[NSKeyedUnarchiver alloc]initForReadingWithData:MyData];    //3:反归档    person *aper = [person new];    aper = [unarchiver decodeObjectForKey:@"person"];    //4:结束归档    [unarchiver finishDecoding];    NSLog(@"%@",aper.name);}

#pragma mark----对foundation框架中的对象进行归档和反归档- (void)fundationClass{//归档    //1:创建路径    NSString *Doucuments = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)firstObject];    NSString *path = [Doucuments stringByAppendingString:@"file.plist"];    //2:归档(不需要结束方法)    NSArray *array = @[@"jiajia",@"jiejie",@"pangpang"];    BOOL result = [NSKeyedArchiver archiveRootObject:array toFile:path];    if (result) {        NSLog(@"框架中的归档%@",path);    }    //反归档    NSArray *newArray = [NSKeyedUnarchiver unarchiveObjectWithFile:path];    NSLog(@"框架的结档%@",newArray);}

#pragma mark----对自定义的内容进行归档和反归档- (void)customContent{//归档    //1:获取路径    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)firstObject];   path = [path stringByAppendingString:@"custom.plist"];    NSMutableData *data = [NSMutableData data];    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];    [archiver encodeObject:@"111" forKey:@"name"];    [archiver encodeObject:@"2" forKey:@"gender"];    [archiver encodeObject:@"100" forKey:@"age"];    [archiver finishEncoding];    BOOL result = [data writeToFile:path atomically:YES];    if (result) {        NSLog(@"归档%@",path);    }    NSData *newdata = [NSData dataWithContentsOfFile:path];    NSKeyedUnarchiver *unkeyed =  [[NSKeyedUnarchiver alloc]initForReadingWithData:newdata];//    NSString *str1 = [unkeyed decodeObjectForKey:@"name"];//    NSString *str2 = [unkeyed decodeObjectForKey:@"gender"];//    NSString *str3 = [unkeyed decodeObjectForKey:@"age"];    person *pp = [person new];    pp.name = [unkeyed decodeObjectForKey:@"name"];    pp.gender = [unkeyed decodeObjectForKey:@"gender"];    pp.age = [unkeyed decodeObjectForKey:@"age"];    [unkeyed finishDecoding];    NSLog(@"name:%@ gender:%@ age:%@",pp.name,pp.gender,pp.age);//    NSLog(@"name:%@ gender:%@ age:%@",str1,str2,str3);

}

文／钎探穗（简书作者）
原文链接：http://www.jianshu.com/p/df801df8169e
著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。