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