iPhone應用開發之模型對象歸檔

iPhone應用開發之模型對象歸檔是本文要介紹的內容，主要是來介紹歸檔，它指的是另一種型式的序列化，但它是任保對象都可以實現的更常規的類型。其作用為：進行資料的持久化儲存。來看詳細內容。

對象必須實現NSCodeing協議和NSCopying協議。

 

  
@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;  
  
} 
 

擷取歸檔檔案

 

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

對資料進行歸檔

 

  
FourLines *fourLines = [[FourLines alloc] init];  
  
    fourLines.field1 = field1.text;  
  
    fourLines.field2 = field2.text;  
  
    fourLines.field3 = field3.text;  
  
    fourLines.field4 = field4.text;  
  
//對資料進行歸檔  
  
    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];    
 

擷取歸檔資料

 

  
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];         
  
} 
 

小結：iPhone應用開發之模型對象歸檔的內容介紹完了，希望通過本文對你有所協助！