ios - 抛出异常观察 NSManagedObjectContext 保存

Question

我得到以下异常 An observer of NSManagedObjectContextDidSaveNotification illegally threw an exception. Objects saved = {
inserted = "{(\n)}";
updated = "{(\n <FJCDSeriesPreferences: 0x1744b30e0> (entity: SeriesPreferences; id: 0xd000000000700012 <x-coredata://29345DF0-9D92-410F-9305-84BFA1672BB9/SeriesPreferences/p28> ; data: {\n isFavourite = 0;\n region = us;\n series = \"0xd00000000d840010 <x-coredata://29345DF0-9D92-410F-9305-84BFA1672BB9/Series/p865>\";\n seriesID = 955129;\n})\n)}";
} and exception = [<FJCDSeriesPreferences 0x1744b30e0> valueForUndefinedKey:]: the entity SeriesPreferences is not key value coding-compliant for the key "program". with userInfo = {
NSTargetObjectUserInfoKey = "<FJCDSeriesPreferences: 0x1744b30e0> (entity: SeriesPreferences; id: 0xd000000000700012 <x-coredata://29345DF0-9D92-410F-9305-84BFA1672BB9/SeriesPreferences/p28> ; data: {\n isFavourite = 0;\n region = us;\n series = \"0xd00000000d840010 <x-coredata://29345DF0-9D92-410F-9305-84BFA1672BB9/Series/p865>\";\n seriesID = 955129;\n})";
NSUnknownUserInfoKey = program;
}

这是导致问题的代码

-(void)contextDidUpdate:(NSNotification *)note{
    NSManagedObjectContext *incomingContext = [note object];
    NSDictionary *userInfo = [[note userInfo] copy];
    if (self.context != incomingContext){
        //Do not track
        return;
    }
predicateWithFormat:@"program.objectId IN %@", _objectsToFetch];
    NSPredicate *programIDPredicate = [NSPredicate predicateWithFormat:@"%K like %@", @"program.objectId", _objectsToFetch ];

    NSSet *inserted = [userInfo objectForKey:@"inserted"];
    if ([inserted count]){
        //objects have been inserted
        self.insertedObjectsBlock([inserted allObjects]);

    }

    NSSet *deleted = [[[userInfo objectForKey:@"deleted"] copy ]filteredSetUsingPredicate:programIDPredicate];
    if ([deleted count]){
        //objects have been deleted
        self.deletedObjectsBlock([deleted allObjects]);
    }

    NSSet *updated = [[[userInfo objectForKey:@"updated"] copy]filteredSetUsingPredicate:programIDPredicate];
    if ([updated count]){
        //objects have been updated
        self.updatedObjectsBlock([updated allObjects]);
    }   
}

问题发生在谓词周围，因为并非所有正在更新键值的实体都与 IM 尝试访问的属性兼容。 IM 试图做的是查找已更改的对象，并查看它们是否与特定关系相关，在本例中查看偏好是否与程序相关。

Answer 1

您的谓词有问题。如果无法直接用调试器戳它，您似乎正在对不响应这些方法的对象调用 program.objectId。如果您尝试访问 NSManagedObjectID，那么您输入错误，因为该方法是 objectID 而不是 objectId。

为了捕获这一点，我建议在使用谓词之前放置一个断点，并打印出每个集合中的内容，并确认您得到了您期望得到的结果。

顺便说一句，那些对 -copy 的调用是多余和浪费的。