数据持久化之NSKeyedArchiver

基本的数据类型如NSString、NSDictionary、NSArray、NSData、NSNumber等可以用属性列表的方法持久化到.plist 文件中，但如果是一些自定义的类的话，属性列表的方法就不管用了。archiver 方法可以做到。

编码如下：
首先新建一个person类，定义它的三个属性，如下：
[cpp] view plaincopyprint?
//
// person.h
// 数据持久化之archiver
//
// Created by Rio.King on 13-9-22.
// Copyright (c) 2013年 Rio.King. All rights reserved.
//

import <UIKit/UIKit.h>

@interface person : UIView
@property(nonatomic, assign) int age;
@property(nonatomic, copy)NSString *name;
@property(nonatomic, assign)float height;
@end

[cpp] view plaincopyprint?
//
// person.m
// 数据持久化之archiver
//
// Created by Rio.King on 13-9-22.
// Copyright (c) 2013年 Rio.King. All rights reserved.
//

import "person.h"

@implementation person

pragma mark 写入文件

-(void)encodeWithCoder:(NSCoder *)encoder{
[super encodeWithCoder:encoder];//不要忘了这个
[encoder encodeInt:self.age forKey:@"age"];
[encoder encodeObject:self.name forKey:@"name"];
[encoder encodeFloat:self.height forKey:@"height"];
}

pragma mark 从文件中读取

-(id)initWithCoder:(NSCoder *)decoder{
self = [super initWithCoder:decoder];//不要忘了这个
self.age = [decoder decodeIntForKey:@"age"];
self.name = [decoder decodeObjectForKey:@"name"];
self.height = [decoder decodeFloatForKey:@"height"];

return self;  

}

-(NSString *)description{
return [NSString stringWithFormat:@"name = %@, age = %d, height = %f",self.name,self.age,self.height];
}

//释放资源
-(void)dealloc{
[super dealloc];
[_name release];
}
@end

然后再ViewController.m文件中写如下代码：
[cpp] view plaincopyprint?
//
// ViewController.m
// 数据持久化之archiver
//
// Created by Rio.King on 13-9-22.
// Copyright (c) 2013年 Rio.King. All rights reserved.
//

import "ViewController.h"

import "person.h"

@interface ViewController ()

@end

@implementation ViewController

• (void)viewDidLoad
  {
  [super viewDidLoad];
  [self createPerson];
  [self readPerson];
  }

//创建
-(void)createPerson{

person *p = [[[person alloc] init] autorelease];  
p.age = 20;  
p.name = @"Rio";  
p.height =1.75f;  
  
//获得Document的路径  
NSString *documents = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];  
NSString *path = [documents stringByAppendingPathComponent:@"person.archiver"];//拓展名可以自己随便取  
  
[NSKeyedArchiver archiveRootObject:p toFile:path];  

}

//读取
-(void)readPerson{
NSString *documents = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *path = [documents stringByAppendingPathComponent:@"person.archiver"];
person *person1 = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
NSLog(@"%@",person1);
}

@end

，，在写ViewController.m文件代码的时候，必须在头文件中遵循NSCoding协议。
[cpp] view plaincopyprint?

import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@end

运行结果如下:
2013-09-22 13:31:39.509 数据持久化之archiver[1080:c07] name = Rio, age = 20, height = 1.750000