IPhone之模型对象归档

@interface FourLines : NSObject <NSCoding, NSCopying> {

NSString *field1;

NSString *field2;

NSString *field3;

NSString *field4;

}

@property (nonatomic, retain) NSString *field1;

@property (nonatomic, retain) NSString *field2;

@property (nonatomic, retain) NSString *field3;

@property (nonatomic, retain) NSString *field4;

@end
#pragma mark NSCoding

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

[encoder encodeObject:field1
forKey:kField1Key];

[encoder encodeObject:field2
forKey:kField2Key];

[encoder encodeObject:field3
forKey:kField3Key];

[encoder encodeObject:field4
forKey:kField4Key];

}

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

if (self = [super init]) {

self.field1 = [decoder
decodeObjectForKey:kField1Key];

self.field2 = [decoder
decodeObjectForKey:kField2Key];

self.field3 = [decoder
decodeObjectForKey:kField3Key];

self.field4 = [decoder
decodeObjectForKey:kField4Key];

}

return self;

}
#pragma mark NSCopying

- (id)copyWithZone:(NSZone *)zone {

FourLines *copy = [[[self class] allocWithZone:
zone] init];

copy.field1 = [[self.field1 copyWithZone:zone]
autorelease];

copy.field2 = [[self.field2 copyWithZone:zone]
autorelease];

copy.field3 = [[self.field3 copyWithZone:zone]
autorelease];

copy.field4 = [[self.field4 copyWithZone:zone]
autorelease];

return copy;

}

- (NSString *)dataFilePath {

NSArray *paths =
NSSearchPathForDirectoriesInDomains( NSDocumentDirectory,
NSUserDomainMask, YES);

NSString *documentsDirectory = [paths
objectAtIndex:0];

return [documentsDirectory
stringByAppendingPathComponent:@"archive"];

}

FourLines *fourLines = [[FourLines alloc] init];

fourLines.field1 = field1.text;

fourLines.field2 = field2.text;

fourLines.field3 = field3.text;

fourLines.field4 = field4.text;

//对数据进行归档

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

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

[archiver encodeObject:fourLines
forKey:@"Data"];

[archiver finishEncoding];

[data writeToFile:[self dataFilePath]
atomically:YES];

[fourLines release];

[archiver release];

[data release];

NSString *filePath = [self dataFilePath];

if ([[NSFileManager defaultManager]
fileExistsAtPath:filePath]) {

NSData *data =
[[NSMutableData alloc]

initWithContentsOfFile:[self
dataFilePath]];

NSKeyedUnarchiver
*unarchiver = [[NSKeyedUnarchiver alloc]

initForReadingWithData:data];

FourLines *fourLines =
[unarchiver decodeObjectForKey:@"Data"];

[unarchiver
finishDecoding];

field1.text =
fourLines.field1;

field2.text =
fourLines.field2;

field3.text =
fourLines.field3;

field4.text =
fourLines.field4;

[unarchiver
release];

[data
release];

}