iOS 数据持久化二－对象归档

iOS中有五种持久化数据的方式：属性列表、对象归档、NSUserDefaults、SQLite3和Core Data。

本文介绍对象归档来持久化数据。归档的作用就是将对象以文件的形式保存到磁盘中，以使得数据序列化和持久化。

使用归档的时候读取该文件保存路径来读取文件的内容，归档的文件是进行过保密处理的，在磁盘上是无法查看文件的内容的，这也是和属性列表的区别：属性列表是明文，可以直接从磁盘查看其内容。

使用归档需要使用NSCoding协议中的代理两个方法

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@protocol NSCoding

- (void)encodeWithCoder:(NSCoder *)aCoder;

- (id)initWithCoder:(NSCoder *)aDecoder;

@end

自定义类进行归档：

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//

// ScoreCard.h

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import <Foundation/Foundation.h>

//遵循NSCoding协议

@interface ScoreCard : NSObject<NSCoding>

{

NSString *_bestTime;

NSMutableArray *_allTimes;

}

@property (copy, nonatomic) NSString *bestTime;

@property (copy) NSMutableArray *allTimes;

@end

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//

// ScoreCard.m

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import "ScoreCard.h"

@implementation ScoreCard

@synthesize bestTime = _bestTime;

@synthesize allTimes = _allTimes;

- (void)dealloc

{

[_bestTime release];

[_allTimes release];

[super dealloc];

}

- (id)init

{

if (self = [super init]) {

_bestTime = [[NSString alloc] init];

_allTimes = [[NSMutableArray alloc] init];

}

return self;

}

//解码方法

- (id)initWithCoder:(NSCoder *)aDecoder

{

if (self = [super init]) {

_bestTime = [[aDecoder decodeObjectForKey:@"bestTime"] retain];

_allTimes = [[aDecoder decodeObjectForKey:@"allTimes"] retain];

}

return self;

}

//编码方法

- (void)encodeWithCoder:(NSCoder *)aCoder

{

[aCoder encodeObject:_bestTime forKey:@"bestTime"];

[aCoder encodeObject:_allTimes forKey:@"allTimes"];

}

@end

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//

// Athlete.h

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import <Foundation/Foundation.h>

@class ScoreCard;

//遵守NSCoding 协议

@interface Athlete : NSObject<NSCoding>

{

NSString *_name;

NSString *_bio;

NSString *_phoneNumber;

ScoreCard *_scoreCard;

BOOL _eligible;

}

@property (copy) NSString *name, *bio, *phoneNumber;

@property (retain) ScoreCard *scoreCard;

@property (getter = isEligible) BOOL eligible;

- (void)print;

@end

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//

// Athlete.m

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import "Athlete.h"

#import "ScoreCard.h"

@implementation Athlete

@synthesize name = _name, bio = _bio, phoneNumber = _phoneNumber, scoreCard = _scoreCard, eligible = _eligible;

- (void)dealloc

{

[_name release];

[_bio release];

[_scoreCard release];

[super dealloc];

}

- (id)init

{

if (self = [super init]) {

_name = [[NSString alloc] init];

_bio = [[NSString alloc] init];

_phoneNumber = [[NSString alloc] init];

_scoreCard = [[ScoreCard alloc] init];

_eligible = YES;

}

return self;

}

//解码方法

- (id)initWithCoder:(NSCoder *)aDecoder

{

if (self = [super init]) {

_name = [[aDecoder decodeObjectForKey:@"name"] retain];

_bio = [[aDecoder decodeObjectForKey:@"bio"] retain];

_scoreCard = [[aDecoder decodeObjectForKey:@"scoreCard"] retain];

//BOOL类型变量解码

_eligible = [aDecoder decodeBoolForKey:@"eligible"];

}

return self;

}

//编码方法

- (void)encodeWithCoder:(NSCoder *)aCoder

{

[aCoder encodeObject:_name forKey:@"name"];

[aCoder encodeObject:_bio forKey:@"bio"];

[aCoder encodeObject:_scoreCard forKey:@"scoreCard"];

//BOOL类型变量归档

[aCoder encodeBool:_eligible forKey:@"eligible"];

}

- (void)print

{

NSLog(@"Name: %@\nBio: %@\nTel: %@\n\nBest Time: %@\n\nAll Times:", _name, _bio, _phoneNumber, [_scoreCard bestTime]);

for (NSString *time in [_scoreCard allTimes]) {

NSLog(@"%@", time);

}

}

@end

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//

// Roster.h

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import <Foundation/Foundation.h>

@class Athlete;

//遵循归档NSCoding协议

@interface Roster : NSObject<NSCoding>

{

NSMutableArray *_athletes;

int _rank;

}

@property (retain) NSMutableArray *athletes;

@property int rank;

- (void)create;

- (void)print;

- (void)addAthlete:(Athlete *)athlete;

@end

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//

// Roster.m

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import "Roster.h"

#import "ScoreCard.h"

#import "Athlete.h"

static NSString *names [] = { @"John Doe",

@"Jane Doe", @"Shaun White", @"Jeff Beck",

@"Eric Clapton", @"Angus Young", @"Flavius Josephus" };

@implementation Roster

@synthesize athletes = _athletes, rank = _rank;

- (void)dealloc

{

[_athletes release];

[super dealloc];

}

- (void)create

{

NSMutableArray *scoreArray = [NSMutableArray arrayWithObjects:@"21:32:21", @"12:48:11", @"16:11:32", nil nil];

for(int i = 0; i < 7; ++i){

Athlete *athlete = [[Athlete alloc] init];

athlete.name = names[i];

athlete.bio = @"I'm a boss";

[athlete setPhoneNumber:@"321-3241"];

athlete.scoreCard.bestTime = @"12:30:22";

athlete.scoreCard.allTimes = scoreArray;

[self addAthlete:athlete];

[athlete release];

}

}

- (id)init

{

if (self = [super init]) {

_rank = 0;

_athletes = [[NSMutableArray alloc] init];

}

return self;

}

//解码方法

- (id)initWithCoder:(NSCoder *)aDecoder

{

if (self = [super init]) {

_athletes = [[aDecoder decodeObjectForKey:@"athletes"] retain];

//解码int类型变量

_rank = [aDecoder decodeIntForKey:@"rank"];

}

return self;

}

- (void)encodeWithCoder:(NSCoder *)aCoder

{

[aCoder encodeObject:_athletes forKey:@"athletes"];

[aCoder encodeInt:_rank forKey:@"rank"];

}

- (void)addAthlete:(Athlete *)athlete

{

[_athletes addObject:athlete];

}

- (void)print

{

NSLog(@"Roster info:\nRank: %d", _rank);

for (Athlete *athlete in _athletes) {

NSLog(@"%@", [athlete name]);

}

}

@end

在main函数里面进行归档

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//

// main.m

// ArchiverDemo

//

// Created by swplzj on 13-11-19.

// Copyright (c) 2013年 swplzj. All rights reserved.

//

#import <UIKit/UIKit.h>

#import "Roster.h"

#define ARCHIVE 0

#define UNARCHIVE 1

int main(int argc, charchar *argv[])

{

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

//获得根路径

NSString *homePath = [[NSBundle mainBundle] executablePath];

//按照“/”分解字符串到数组

NSArray *strings = [homePath componentsSeparatedByString:@"/"];

//

NSString *executbleName = [strings objectAtIndex:[strings count] - 1];

NSString *baseDirectory = [homePath substringToIndex:[homePath length] - [executbleName length] - 1];

//文件名字

NSString *fileName = [NSString stringWithFormat:@"%@/roster.archive", baseDirectory];

NSLog(@"filePath: %@", fileName);

#if ARCHIVE

//创建并归档一个roster

Roster *roster = [[Roster alloc] init];

[roster create];

//把对象写到二进制流中去

[NSKeyedArchiver archiveRootObject:roster toFile:fileName];

[roster release];

#endif

#if UNARCHIVE

//已经写入到磁盘，直接从二进制流读取对象

Roster *unarchive = [NSKeyedUnarchiver unarchiveObjectWithFile:fileName];

[unarchive print];

for (Athlete *athlete in [unarchive athletes]) {

[athlete print];

}

[unarchive release];

#endif

[pool release];

return 0;

}

运行程序，前往文件夹：

/Users/issuser/Library/Application Support/iPhone Simulator/6.1/Applications/74C8943C-BE5F-4BB7-8385-8E922AF29589/ArchiverDemo.app/roster.archive

归档成功。点击这里下载ArchiverDemo



这就是使用归档来达到数据的持久化。你也来试试吧。