NSCoder對象編碼和解碼

轉自: http://o0o0o0o.javaeye.com/blog/588889

// codeObj.h

// encodeObject

// Created by 110 on 10-2-6.

#import <Cocoa/Cocoa.h>

@interface codeObj : NSObject <NSCoding>{

NSString *name;

int magicNumber;

float shoseSize;

NSMutableArray *subThingies;

}

@property (copy) NSString *name;

@property int magicNumber;

@property float shoseSize;

@property (retain) NSMutableArray *subThingies;

-(id) initwithName:(NSString *) n

magicNumber:(int) mn shoseSize:(float) ss;

@end

// codeObj.m

// encodeObject

// Created by 110 on 10-2-6.

#import "codeObj.h"

@implementation codeObj

@synthesize name;

@synthesize magicNumber;

@synthesize shoseSize;

@synthesize subThingies;

-(id) initwithName:(NSString *) n

magicNumber:(int) mn shoseSize:(float) ss{

if(self=[super init]){

self.name=n;

self.magicNumber=mn;

self.shoseSize=ss;

self.subThingies=[NSMutableArray array];

}

return (self);

}

-(void) dealloc{

[name release];

[subThingies release];

[super dealloc];

}

//nscoding協議的方法

-(void) encodeWithCoder:(NSCoder *) coder{

[coder encodeObject:name forKey:@"name"];

[coder encodeInt:magicNumber forKey:@"magicNumber"];

[coder encodeFloat:shoseSize forKey:@"shoseSize"];

[coder encodeObject:subThingies forKey:@"subThingies"];

}

-(id) initWithCoder:(NSCoder *) decoder{

if(self =[super init]){

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

self.magicNumber=[decoder decodeIntForKey:@"magicNumber"];

self.shoseSize=[decoder decodeFloatForKey:@"shoseSize"];

self.subThingies=[decoder decodeObjectForKey:@"subThingies"];

}

return (self);

}

-(NSString *) description{

NSString *descripton=[NSString stringWithFormat:@"%@:%d,%.1f,%@",name,magicNumber,

shoseSize,subThingies];

return (descripton);

}

@end

#import "codeObj.h"

int main (int argc, const char * argv[]) {

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

codeObj *thing;

thing=[[[codeObj alloc] initwithName:@"name" magicNumber:20 shoseSize:30.5] autorelease];

NSLog(@"--------%@",thing);

NSData *freezeDrid;

freezeDrid=[NSKeyedArchiver archivedDataWithRootObject:thing];

[freezeDrid writeToFile:@"/tmp/codeobj.txt" atomically:YES];

codeObj *anotherThing;

anotherThing=[[[codeObj alloc] initwithName:@"ssssss" magicNumber:20 shoseSize:4.5] autorelease];

[anotherThing.subThingies addObject:thing];

NSData *other;

other=[NSKeyedArchiver archivedDataWithRootObject:anotherThing];

//寫入文件

[other writeToFile:@"/tmp/objandobj.txt" atomically:YES];

//從文件中讀取

NSData *fileData;

fileData=[NSData dataWithContentsOfFile:@"/tmp/objandobj.txt"];

codeObj *fromFile;

fromFile=[NSKeyedUnarchiver unarchiveObjectWithData:fileData];

NSLog(@"------%@",fromFile);

[pool drain];

return 0;

}

讀後感：在自己的類中實現NScoding協議作用是使自己的類支持“由類轉換到NSData”的功能（僅是添加支持）。而真正實現此功能的是NSKeyedUnarchiver的unarchiveObjectWithData和NSKeyedArchiver的archivedDataWithRootObject。（類到NSData的轉化）

下面是另一種NScoder用法。

//
//  UserEntity.m
//  NSCodingDemo
//
//  Created by   on 11-5-20.
//  Copyright 2011  , Inc. All rights reserved.
//

#import "UserEntity.h"
#import "AddressEntity.h"

#define SAMPLEDATA_KEY_USERNAME (@"userName")
#define SAMPLEDATA_KEY_GENDER (@"gender")
#define SAMPLEDATA_KEY_AGE (@"age")
#define k_FRIENDS (@"frinds")
#define k_ADDRESS (@"address")
#define k_userEntity_addresses (@"addresses")

@implementation UserEntity
@synthesize userName = _userName;
@synthesize gender   = _gender;
@synthesize age      = _age;
@synthesize friends  = _friends;
@synthesize address  = _address;
@synthesize addresses = _addresses;

-(void)dealloc
{
    [self.userName release];
    [self.friends release];
    [self.address release];
    [self.addresses release];
    [super dealloc];
}

  - (void)encodeWithCoder:(NSCoder*)coder
  {
      [coder encodeObject:self.userName forKey:SAMPLEDATA_KEY_USERNAME];
      [coder encodeInt:self.age forKey:SAMPLEDATA_KEY_AGE];
      [coder encodeBool:self.gender forKey:SAMPLEDATA_KEY_GENDER];
      [coder encodeObject:self.friends forKey:k_FRIENDS];
      [coder encodeObject:self.address forKey:k_ADDRESS];
      [coder encodeObject:self.addresses forKey:k_userEntity_addresses];
  }

  - (id)initWithCoder:(NSCoder*)decoder
  {
      if (self = [super init])
      {
          if (decoder == nil)
          {
              return self;
          }
          self.userName = [decoder decodeObjectForKey:SAMPLEDATA_KEY_USERNAME];
          self.gender = [decoder decodeBoolForKey:SAMPLEDATA_KEY_GENDER];
          self.age = [decoder decodeIntForKey:SAMPLEDATA_KEY_AGE];
          self.friends = [decoder decodeObjectForKey:k_FRIENDS];
          self.address = [decoder decodeObjectForKey:k_ADDRESS];
          self.addresses = [decoder decodeObjectForKey: k_userEntity_addresses];
      }
      return self;
  }

@end

#import "AddressEntity.h"
#define k_Id (@"id")
#define k_AddresEntity_address (@"addrss")

@implementation AddressEntity
@synthesize Id, address;
-(void)dealloc
{
    [self.address release];
    [super dealloc];
}
- (NSString *)description
{

    return [NSString stringWithFormat:@"id :%d address: %@" , self.Id, self.address];
}

- (void)encodeWithCoder:(NSCoder*)coder
{
    [coder encodeObject:self.address forKey:k_AddresEntity_address];
    [coder encodeInt:self.Id forKey:k_Id];

}

- (id)initWithCoder:(NSCoder*)decoder
{
    if (self = [super init])
    {
        if (decoder == nil)
        {
            return self;
        }
        self.address = [decoder decodeObjectForKey:k_AddresEntity_address];
        self.Id = [decoder decodeIntForKey:k_Id];

    }
    return self;
}
@end

-(IBAction)write:(id)sender
{
    //get document path
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString *filePath = [documentsDirectory stringByAppendingPathComponent:k_FILE_NAME];

    NSMutableData *data = [[[NSMutableData alloc] init] autorelease];
    NSKeyedArchiver *archiver = [[[NSKeyedArchiver alloc] initForWritingWithMutableData:data] autorelease];
    UserEntity *userEntity = [[[UserEntity alloc] init] autorelease];
    userEntity.age = 18;
    userEntity.gender = NO;
    userEntity.userName = @"add";

    NSArray *friends = [[NSArray alloc] initWithObjects:@"ac", @"2", @"3", @"4", nil];
    userEntity.friends = friends;

    AddressEntity *address = [[[AddressEntity alloc] init] autorelease];
    address.Id = 1;
    address.address = @"china";
    userEntity.address = address;

    AddressEntity *address2 = [[[AddressEntity alloc] init] autorelease];
    address2.Id = 2;
    address2.address = @"china2";

    AddressEntity *address3 = [[[AddressEntity alloc] init] autorelease];
    address3.Id = 3;
    address3.address = @"china3";

    NSArray *addresses = [[NSArray alloc] initWithObjects:address2, address3 , nil];

    userEntity.addresses = addresses;

    [archiver encodeObject:userEntity forKey:@"KEY"];
    [archiver finishEncoding];
    BOOL success = [data writeToFile:filePath atomically:YES];


}

-(IBAction)read:(id)sender
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString *filePath = [documentsDirectory stringByAppendingPathComponent:k_FILE_NAME];

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

    NSKeyedUnarchiver *unArchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    UserEntity *userEntity = [unArchiver decodeObjectForKey:@"KEY"];
    NSLog(@"name is %@ , friend %@ address :%@ , addresses is :%@", userEntity.userName , userEntity.friends , userEntity.address, userEntity.addresses);

}