关于数据的归档存入文件和读取文件

需求：我们都知道NSArry中如果存放的是普通的字符串类型，是很容易存入到plist文件中，也很容易从文件中读取出来，那如果NSArray中存放的是自定义的Person对象呢？该如何存入文件中去呢？

下面我来简单写一个NSArray中继承了NSCoding协议的自定义Person对象，将这个array数组存入到plist文件中，并且能够实现读取文件中的数据的Demo

实现步骤：

1.创建一个SingleView的项目命名为test，然后创建一个自定义的Person对象，具有NSString *name和int age两个属性。

Person.h:

#import <Foundation/Foundation.h>

@interface Person : NSObject<NSCopying,NSCoding>

@property(copy,nonatomic)NSString *name;

@property(assign,nonatomic) int age;

@end

Person.m:

#import "Person.h"



@implementation Person



-(id)copyWithZone:(NSZone *)zone

{

    Person  *p = [[Person alloc] init];  //拷贝函数不需要release,这里用autorelease会报错

    p.name = [self.name copy];

    p.age = self.age;

    return p;

}



//实现NSCoding协议

-(void)encodeWithCoder:(NSCoder *)aCoder

{

    [aCoder encodeObject:self.name forKey:@"name"];

    [aCoder encodeInt:self.age forKey:@"age"]; //这儿要根据不同的类型来写encode的类型

}

//反序列化提取成员变量

-(id)initWithCoder:(NSCoder *)aDecoder

{

    if (self = [super init]) {

        if (aDecoder == nil) {

            return self;

        }

        self.name = [aDecoder decodeObjectForKey:@"name"];

        self.age = [aDecoder decodeIntForKey:@"age"]; //这儿也是，如果是int类型就写decodeIntForKey

    }

    return self;

}



-(NSString *)description

{

    return [NSString stringWithFormat:@"%@,%d",self.name,self.age];

}



@end

2.创建一个ViewController来实现数据的的保存

ViewController.h:

#import <UIKit/UIKit.h>

#import "Person.h"  

@interface DXWViewController : UIViewController

@property(nonatomic,retain)NSArray *Array;

@property(nonatomic,retain)Person *per;

@end

ViewController.m:

#import "DXWViewController.h"

#define kSaveKeyMarkerLines (@"person")

@interface DXWViewController ()



@end



@implementation DXWViewController



-(NSString *)getPath

{

    //用来获得Document地址

	NSArray *arr = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);//注意：这里是NSDocument不是NSDocumentation,特别注意

    NSLog(@"%@",arr);

    //在地址上增加文件

    NSString *path = [arr[0] stringByAppendingPathComponent:@"Person.plist"];

    NSLog(@"%@",path);

    return path;

}



//传入可变数组和地址

//序列化数据

- (BOOL)saveMarkers:(NSMutableArray *)markers toFilePath:(NSString *)filePath

{

    BOOL f;

    NSMutableData *data = [[NSMutableData alloc] init];

    NSKeyedArchiver *vdArchiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];

    [vdArchiver encodeObject:markers forKey:kSaveKeyMarkerLines];

    [vdArchiver finishEncoding];

    f = [data writeToFile:filePath atomically:YES];

    [vdArchiver release];

    [data release];

    return f;

}

//传入地址，返回可变数组

//反序列化数据

- (NSMutableArray *)loadMarkersFromFilePath:(NSString *)filePath {

    NSMutableArray *markers = nil;

    if (filePath == nil || [filePath length] == 0 ||

        [[NSFileManager defaultManager] fileExistsAtPath:filePath] == NO) {

        markers = [[[NSMutableArray alloc] init] autorelease];

    } else {

        NSData *data = [[NSData alloc] initWithContentsOfFile:filePath];

        NSKeyedUnarchiver *vdUnarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];

        markers = [vdUnarchiver decodeObjectForKey:kSaveKeyMarkerLines];

        NSLog(@"++++%@",markers);

        [vdUnarchiver finishDecoding];

        [vdUnarchiver release];

        [data release];

    }

    return markers;

}





- (void)viewDidLoad

{

    [super viewDidLoad];

	Person *p1 = [[Person alloc] init];

    p1.name = @"dingxiaowei";

    p1.age = 22;

    Person *p2 = [[Person alloc] init];

    p2.name = @"wangning";

    p2.age = 33;

    self.Array  = [NSArray arrayWithObjects:p1,p2, nil];

    //保存到文件

    [self saveMarkers:self.Array toFilePath:[self getPath]];

    //从文件中获取数据

    NSMutableArray *arr = [self loadMarkersFromFilePath:[self getPath]];

    NSLog(@"归档后提取的数据:\n%@",arr);

}





@end

如何寻找创建在沙盒中的文件？

点击一下mac机上的前往功能菜单->然后按下Alt键，会跳出一个资源库的一个隐藏文件->Application Support->iPhone Simulator->6.1(看你当前运行的模拟器的版本)->Applications->对应的文件->Documents->xxx.plist

Demo源码：

http://download.csdn.net/detail/s10141303/6013361

运行结果：

2013-08-26 14:04:47.101 test[1442:c07]归档后提取的数据:

(

    "dingxiaowei,22",

    "wangning,33"

)