!!! Listings zum Artikel "Kernansicht"
!!! von Karl Bank aus iX 5/2012, S. 150

!!! Listing 1: Implementierung einer Löschmethode

- (IBAction) deleteAll:(id) sender {
    NSManagedObjectContext* context = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context];
    [fetchRequest setEntity:entity];
    NSError *error = nil;
    NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
    [fetchRequest release];
    for (int nextIndex=0; nextIndex<[fetchedObjects count]; nextIndex++) {
        [context deleteObject:[fetchedObjects objectAtIndex:nextIndex]];
    }
    [context commitEditing];
}

!!! Listing 2: Importieren externer Daten

// Import CSV Data from a file in a given format
- (IBAction) importData:(id) sender {
    NSString *path = @"/Users/karlbanke/Desktop/importdata.txt";
    NSData *data = [NSData dataWithContentsOfFile:path];
    // assuming data is in UTF8
    NSString *fileContent = [NSString stringWithUTF8String:[data bytes]];
    // Each line is a new object
    NSManagedObjectContext *context = [self managedObjectContext];
    NSArray *lines = [fileContent componentsSeparatedByCharactersInSet:
                      [NSCharacterSet newlineCharacterSet]];
    for (int li=0;li<[lines count];li++) {
        NSString *nextLine = [lines objectAtIndex:li];
        NSArray  *entries = [nextLine componentsSeparatedByString:@";"];
        NSObject *nextPerson 
            = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:context];
        NSObject *nextAddress 
            = [NSEntityDescription insertNewObjectForEntityForName:@"Address" inManagedObjectContext:context];
        [nextAddress setValue:nextPerson forKey:@"owner"];
        for (int ei=0;ei<[entries count];ei++) {
            NSString *nextField = [entries objectAtIndex:ei];
            switch (ei) {
                case 0: [nextPerson setValue:nextField forKey:@"lastName"];
                    break;
                case 1: [nextPerson setValue:nextField forKey:@"firstName"];
                    break;
                case 2: [nextAddress setValue:nextField forKey:@"addressLine1"];
                    break;
                case 3: [nextAddress setValue:nextField forKey:@"postcode"];
                    break;
                case 4: [nextAddress setValue:nextField forKey:@"city"];
                    break;
            }
        }
    }
    [context commitEditing];    
}

!!! Listing 3: Alle Felder vorgegeben

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@interface Phone : NSManagedObject {
@private
}
@property (nonatomic, retain) NSString * areaCode;
@property (nonatomic, retain) NSString * countryCode;
@property (nonatomic, retain) NSString * extension;
@property (nonatomic, retain) NSString * phoneNumber;
@property (nonatomic, retain) NSManagedObject *owner;

@end

!!! Listing 4: prettyPhoneNumber und keyPathsForValuesAffectingValueForKey

!!! prettyPhoneNumber / keyPathsForValuesAffectingValueForKey: bitte kursiv

- (NSString*) prettyPhoneNumber {
    NSString *result = [NSString stringWithFormat:@"%@  %@/%@-%@",
                      [self countryCode]!=nil?[self countryCode]:@"",
                      [self areaCode]!=nil?[self areaCode]:@"",
                      [self phoneNumber]!=nil?[self phoneNumber]:@"",
                      [self extension]!=nil?[self extension]:@""
                    ];
    return result;
}

+ (NSSet *)keyPathsForValuesAffectingValueForKey:(NSString *)key
{
    NSSet *keyPaths = [super keyPathsForValuesAffectingValueForKey:key];
    
    if ([key isEqualToString:@"prettyPhoneNumber"])
    {
        NSSet *affectingKeys = [NSSet setWithObjects:@"countryCode", @"phoneNumber", @"areaCode", 
                                @"extension",nil];
        keyPaths = [keyPaths setByAddingObjectsFromSet:affectingKeys];
    }
    return keyPaths;
}