我在删除Core Data
条目时遇到了一些困难。
它可以工作,但NSManagedObject数据没有值(错误),因此有时会删除错误的条目。
在我的 deleteWholeDatabase 方法中,对象用值填充。 并且在 deleteEntryFromDatabase 方法中没有值。但为什么呢?
以下是我的方法:
-(NSArray*)databaseRequest{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:currentEntity inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
[fetchRequest setReturnsObjectsAsFaults:NO];
NSError *error;
NSArray *items = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
return items;
}
-(void)deleteWholeDatabase{
for (NSManagedObject *objectToDelete in [self databaseRequest]) {
[managedObjectContext deleteObject:objectToDelete];
NSLog(@"%@ object deleted",objectToDelete);
}
[self saveContext];
NSLog(@"All entries deleted!");
}
-(void)deleteEntryFromDatabase:(NSManagedObjectContext*)context forEntry:(NSIndexPath*)indexPath{
NSManagedObject *objectToDelete=[[self databaseRequest] objectAtIndex:indexPath.row];
[managedObjectContext deleteObject:[managedObjectContext objectWithID:[objectToDelete objectID]]];
[self saveContext];
NSLog(@"%@ deleted!",[managedObjectContext objectWithID:[objectToDelete objectID]]);
}
答案 0 :(得分:0)
正在删除错误的条目,因为每个请求都以不同的顺序返回itens。尝试通过比较他们的记忆地址来删除强度
答案 1 :(得分:0)
我不会在任何地方保留调用[self databaseRequest]
,而是将NSManagedObjectID's
的本地副本保留为数组。
- (void)init {
self.entities = [self databaseRequest];
}
-(NSArray*)databaseRequest{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:currentEntity inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
[fetchRequest setReturnsObjectsAsFaults:NO];
NSError *error;
NSArray *items = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
NSMutableArray *itemIDs = [[NSMutableArray alloc] initWithCapacity:[items count]];
for (NSManangedObject *item in items) {
[itemIDs addObject:[item objectID]];
}
return items;
}
然后,在您致电[self databaseRequest]
的任何地方,您都会获得正确的NSManagedObjectID
。然后你只需要从ID中获取正确的实体。