iPhone应用开发之模型对象归档

iPhone应用开发之模型对象归档是本文要介绍的内容，主要是来介绍归档，它指的是另一种型式的序列化，但它是任保对象都可以实现的更常规的类型。其作用为：进行数据的持久化保存。来看详细内容。

对象必须实现NSCodeing协议和NSCopying协议。

@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;  
} 

获取归档文件

- (NSString *)dataFilePath {  
    NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);  
    NSString *documentsDirectory = [paths objectAtIndex:0];  
    return [documentsDirectory stringByAppendingPathComponent:@"archive"];  
} 

对数据进行归档

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];    

获取归档数据

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];         
} 

小结：iPhone应用开发之模型对象归档的内容介绍完了，希望通过本文对你有所帮助！