Objective c 在核心数据的某些保存操作中未调用willSave

我有一段代码（可以多次调用，甚至可以同时调用，因为它是为了响应某些NSURLConnection didFinishLoading方法），它应该为上下文中注册的每个对象调用willSave方法

NSLog(@"Before save.");
NSLog(@"Object count: %d", [[managedObjectContext registeredObjects] count]);
[managedObjectContext save:nil];
NSLog(@"After save.");

问题是，willSave（和didSave）方法在最后一次保存操作中只调用一次。我真的不知道这里发生了什么，因为我没有使用线程或类似的东西

上下文中的每个对象都是我自己的MSRemoteObject类的子类，该类具有以下willSave实现：

- (void)willSave {
    [super willSave];

    NSLog(@"Will save.");
}

这是我运行应用程序时生成的日志的一个示例：

2010-07-12 12:07:45.638 Manistone[9902:207] Before save.
2010-07-12 12:07:45.638 Manistone[9902:207] Object count: 1
2010-07-12 12:07:45.643 Manistone[9902:207] Will save.
2010-07-12 12:07:45.650 Manistone[9902:207] Did save.
2010-07-12 12:07:45.651 Manistone[9902:207] After save.
2010-07-12 12:07:46.141 Manistone[9902:207] Before save.
2010-07-12 12:07:46.141 Manistone[9902:207] Object count: 11
2010-07-12 12:07:46.142 Manistone[9902:207] After save.
2010-07-12 12:07:50.574 Manistone[9902:207] Before save.
2010-07-12 12:07:50.574 Manistone[9902:207] Object count: 16
2010-07-12 12:07:50.575 Manistone[9902:207] After save.
2010-07-12 12:07:51.136 Manistone[9902:207] Before save.
2010-07-12 12:07:51.136 Manistone[9902:207] Object count: 18
2010-07-12 12:07:51.136 Manistone[9902:207] After save.
2010-07-12 12:07:51.137 Manistone[9902:207] Before save.
2010-07-12 12:07:51.137 Manistone[9902:207] Object count: 18
2010-07-12 12:07:51.138 Manistone[9902:207] After save.
2010-07-12 12:07:51.144 Manistone[9902:207] Before save.
2010-07-12 12:07:51.144 Manistone[9902:207] Object count: 18
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.145 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.146 Manistone[9902:207] Will save.
2010-07-12 12:07:51.147 Manistone[9902:207] Will save.
2010-07-12 12:07:51.158 Manistone[9902:207] After save.

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我真的想在每次保存操作中触发willSave方法。有什么办法可以强迫你这么做吗？或者是否存在一些我不知道的不调用willSave方法的情况？

问题是只有在保存操作中没有错误时才会调用willSave和didSave。否则它们就被跳过了。我对didSave理解这一点，但对willSave来说，情况不应该如此