Question

如何使用此代码删除之前添加的对象。它是一个收藏夹部分，在开头，我添加了一个灰色的星星，它添加了一个来自fetch的对象。然后它变成黄色，向后的方法应该是黄色的星形=删除。

但我不知道该怎么做。

提前致谢

-(IBAction)inFavoris:(id)sender {



AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSManagedObject *favorisObj = [NSEntityDescription
                            insertNewObjectForEntityForName:@"Favoris"
                            inManagedObjectContext:context];


[favorisObj setValue:idTaxi forKey:@"idTaxi"];
[favorisObj setValue:nomTaxi forKey:@"nomTaxi"];
[favorisObj setValue:taxiCB forKey:@"cb"];
[favorisObj setValue:taxiAvion forKey:@"avion"];
[favorisObj setValue:taxiColis forKey:@"colis"];
[favorisObj setValue:taxiHandicape forKey:@"handicape"];
[favorisObj setValue:taxiHoraires forKey:@"horaire"];
[favorisObj setValue:lugagge forKey:@"lugagge"];
[favorisObj setValue:luxury forKey:@"luxury"];
[favorisObj setValue:languesParlees forKey:@"langues"];
[favorisObj setValue:taxiNote forKey:@"note"];
[favorisObj setValue:taxiPassengers forKey:@"passenger"];
[favorisObj setValue:taxiVote forKey:@"etoiles"];
[favorisObj setValue:taxiTel forKey:@"tel"];


[self.view addSubview:favorisB];

}

更新

我制作了这个方法..它完成了工作：）

-(IBAction)outFavoris:(id)sender {


AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSString *testEntityId = idTaxi;
NSManagedObjectContext *moc2 = [appDelegate managedObjectContext];

NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
fetch.entity = [NSEntityDescription entityForName:@"Favoris" inManagedObjectContext:moc2];
fetch.predicate = [NSPredicate predicateWithFormat:@"idTaxi == %@", testEntityId];
NSArray *array = [moc2 executeFetchRequest:fetch error:nil];




for (NSManagedObject *managedObject in array) {
    [moc2 deleteObject:managedObject];
}


[self.view addSubview:favorisO];

}

Answer 1

非常简单：）

[context deleteObject:favorisObj];

坏的对象全都消失了。

更新

如果你需要一个按钮来删除对象，你可以用这样的东西反转它。

-(IBAction)removeFavoris:(id)sender {

    AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

    NSManagedObjectContext *context = [appDelegate managedObjectContext];

    [context deleteObject:favorisObj];
}

Answer 2

删除NSManagedObject后，不要忘记保存Context。所以这是通用代码;

NSManagedObjectContext * context = [self managedObjectContext];
[context deleteObject:objectToDelete];

NSError * error = nil;
if (![context save:&error])
{
    NSLog(@"Error ! %@", error);
}

在你的情况下，它应该在for循环之后有片段。

for (NSManagedObject *managedObject in array) {
    [moc2 deleteObject:managedObject];
}
NSError * error = nil;
if (![context save:&error])
{
    NSLog(@"Error ! %@", error);
}

删除Core Data中的对象

2 个答案: