abort();//终止程序
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Student" inManagedObjectContext:self.managedObjectContext];
request.entity = entity;
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name = %@",name];
request.predicate = predicate;
NSArray *arr = [self.managedObjectContext executeFetchRequest:request error:nil];
for (Student *stu in arr) {
[self.managedObjectContext deleteObject:stu];
NSLog(@"%@", [self.managedObjectContext deletedObjects]);//这里返回的是 还没有执行删除操作的数据的集合，其他方法同理。
[self.managedObjectContext save:nil];
}