NSCoder对象编码和解码

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

//  codeObj.h

//   encodeObject

//

//   Created by 110 on 10-2-6.

//   Copyright 2010 __MyCompanyName__. All rights reserved.

//

#imp ort <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.

//   Copyright 2010 __MyCompanyName__. All rights reserved.

//

#imp ort "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协议的方法

-(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 archivedDataWithRootObje ct: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 archivedDataWithRootObje ct:anotherThing];

//写入文件

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

//从文件中读取

NSData *fileData;

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

codeObj *fromFile;

fromFile=[NSKeyedUnarchiver unarchiveObjectWithData:fileData];

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

       [pool drain];

       return 0;

}

读后感：在自己的类中实现NScoding协议作用是使自己的类支持“由类转换到NSData”的功能（仅是添加支持）。而真正实现此功能的是NSKeyedUnarchiver的unarchiveObjectWithData和NSKeyedArchiver的archivedDataWithRootObje ct。（类到NSData的转化）


下面是另一种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);
    
}