归档

归档也叫序列化，是将文件存在硬盘，解档是从硬盘还原

5种方式：
第一种、使用属性列表进行归档
如果对象是NSString，NSDictionary,NSArray,NSData或者NSNumber，可以使用writeToFile:atomically方法将数据写到文件,注意这种方式是明文

sample:

NSArray *array = @[@"abc",@"123",@23.4];
if ([array writeToFile:@"text.plist" atomically:YES])
{
    NSLog(@"success");
}
NSArray *arr2=[NSArray arrayWithContentsOfFile:@"text.plist"];
NSLog(@"%@",arr2);

第二、NSKeyedArchiver–对象归档，数据会加密
1、对于NSArray或者NSDictionary sample code：

 /***归档对象****/
  NSArray *array = @[@"abc",@"123",@23.4];
  NSString *homePath = NSHomeDirectory();
  NSString *path = [homePath stringByAppendingPathComponent:@"test.arc”];//设置归档的文件路径

 // BOOL success = [NSKeyedArchiver archiveRootObject:array toFile:path];
  BOOL success=[NSKeyedArchiver archiveRootObject:array toFile:path];
  if (success) {
      NSLog(@"archive success");
        }

  /***解归档****/
  NSArray *array2 =[NSKeyedUnarchiver unarchiveObjectWithFile:path];
NSLog(@"%@",array2);

结果：
success
2013-12-28 22:14:25.353 ArchiverDemo1[1206:303] (
abc,
123,
“23.4”
)

2、如果是其他类型的对象存储到文件，可以利用NSKeyedArchiver类创建带键的档案来完成

NSString *homePath = NSHomeDirectory();
NSString *path = [homePath stringByAppendingPathComponent:@"archiver2.archiv"];
NSMutableData *data = [NSMutableData data];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
NSArray *array = @[@"jack",@"tom"];
[archiver encodeInt:100 forKey:@"age"];
[archiver encodeObject:array forKey:@"names"];
[archiver finishEncoding];
[archiver release];

BOOL success = [data writeToFile:path atomically:YES];
if (success) {
    NSLog(@"archive success");
}

/***解归档对象**/

NSData *data2 = [NSData dataWithContentsOfFile:path];
NSKeyedUnarchiver *unArchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data2];
int age = [unArchiver decodeIntForKey:@"age"];
NSArray *names = [unArchiver decodeObjectForKey:@"names"];
[unArchiver release];
NSLog(@"age=%d,names=%@",age,names);

3、自定义对象进行归档，需要实现归档协议NSCoding两个方法

对属性编码，归档的时候会调用
- (void)encodeWithCoder:(NSCoder *)aCoder
//对属性解码，解归档调用
- (id)initWithCoder:(NSCoder *)aDecoder

//对属性编码，归档的时候会调用
- (void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeInt:_age forKey:AGE];
    [aCoder encodeObject:_name forKey:NAME];
    [aCoder encodeObject:_email forKey:EMAIL];
    [aCoder encodeObject:_password forKey:PASSWORD];

}

//对属性解码，解归档调用
- (id)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    if (self != nil) {
        _age = [aDecoder decodeIntForKey:AGE];
        self.name = [aDecoder decodeObjectForKey:NAME];
        self.email = [aDecoder decodeObjectForKey:EMAIL];
        self.password = [aDecoder decodeObjectForKey:PASSWORD];
    }
    return self;
}

第三种：NSUserDefaults
sample code:

[[NSUserDefaults standardUserDefaults] setObject:authData forKey:@"SinaWeiboAuthData"];
[[NSUserDefaults standardUserDefaults] synchronize];

第四种、SQlite数据库、CoreData数据库