如何更新提取的托管对象？

Question

我在更新核心数据中的特定记录时遇到了麻烦。在我的代码中发生了什么，它确实改变了值，但是当我重新运行应用程序时，它会恢复到原始值。为什么会这样？

NSManagedObjectContext *context = [self managedObjectContext];

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Wish" inManagedObjectContext:context];
[fetchRequest setEntity:entity];
// Specify criteria for filtering which objects to fetch
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"itemWish = %@", self.wishItemStr];
[fetchRequest setPredicate:predicate];
NSError *error = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];

[fetchedObjects setValue:@"YES" forKeyPath:@"isAchieved"];

if (fetchedObjects == nil) {
    NSLog(@"no fetched objects!");
}

Answer 1

您需要save上下文。

[managedObjectContext save:&error];

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