Iphone Coredata错误setObjectForKey:对象不能为零

我正在尝试检查coredata存储中是否有任何数据作为我应用程序的恢复类型。基本上，如果用户处于最终视图中，coredata中的某些数据会不断更新

因此，他们在最终视图中，然后应用程序中断，或者他们将其置于睡眠状态，然后应用程序从内存中删除

下次加载应用程序时，我检查我的coredata对象，查看是否有任何值，如果有，我会提示用户告诉他们，您希望从您停止继续刷新的位置继续未完成的工作

如果他们想重新开始，我会转储我核心数据中当前的任何内容，并允许他们工作。否则，我跳到最后一个视图，加载coredata中的数据，并允许它们继续工作

然而，这就是错误发生的地方，我像这样检查我的coredata

NSMutableArray *checkFinMutableArray = [coreDataController readFin];

    if ([checkFinMutableArray count] > 0) {
        //Show mesage, recover or not?
        UIAlertView *alert = [[UIAlertView alloc] init];
        [alert setTitle:@"Selected projects avalible"];
        [alert setMessage:@"It appears that you have unfinished projects from a previous session. Would you like to continue working on these projects?"];
        [alert setDelegate:self];
        [alert addButtonWithTitle:@"Yes"];
        [alert addButtonWithTitle:@"No"];
        [alert show];
    }

这就是我的coredata对象的外观

 - (NSMutableArray *)readFinDimensions {
        NSManagedObjectContext *context = [self managedObjectContext];


        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
        NSEntityDescription *entity = [NSEntityDescription entityForName:@"Project" inManagedObjectContext:context];
        [fetchRequest setEntity:entity];

        NSError *error;

        NSMutableArray *projectDictionaryArray = [[NSMutableArray alloc] init];


        NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];


        for (ProjectList *projectList in fetchedObjects) {

            NSMutableDictionary *tempProjectDictionaryArray = [[ NSMutableDictionary alloc] init];

            [tempProjectDictionaryArray setObject:project.proj forKey:@"Proj"]; // this is where the ap dies
            [tempProjectDictionaryArray setObject:project.desc forKey:@"Desc"];

            [projectDictionaryArray addObject:tempProjectDictionaryArray];
        }

        return projectDictionaryArray;
    }

 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** setObjectForKey: object cannot be nil (key: Proj)'

这就是错误的样子

 - (NSMutableArray *)readFinDimensions {
        NSManagedObjectContext *context = [self managedObjectContext];


        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
        NSEntityDescription *entity = [NSEntityDescription entityForName:@"Project" inManagedObjectContext:context];
        [fetchRequest setEntity:entity];

        NSError *error;

        NSMutableArray *projectDictionaryArray = [[NSMutableArray alloc] init];


        NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];


        for (ProjectList *projectList in fetchedObjects) {

            NSMutableDictionary *tempProjectDictionaryArray = [[ NSMutableDictionary alloc] init];

            [tempProjectDictionaryArray setObject:project.proj forKey:@"Proj"]; // this is where the ap dies
            [tempProjectDictionaryArray setObject:project.desc forKey:@"Desc"];

            [projectDictionaryArray addObject:tempProjectDictionaryArray];
        }

        return projectDictionaryArray;
    }

 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** setObjectForKey: object cannot be nil (key: Proj)'

---

任何帮助都将不胜感激。

这意味着

project.proj

在

[tempProjectDictionaryArray setObject:project.proj forKey:@"Proj"];

NS（可变）字典

无法将

nil

存储为值，因此您应该检查例如

if (project.proj != nil) {
    [tempProjectDictionaryArray setObject:project.proj forKey:@"Proj"];
}

或者，您可以使用

tempProjectDictionaryArray = [project dictionaryWithValuesForKeys:@[@"Proj", @"Desc"]];

这几乎和

[tempProjectDictionaryArray setObject:project.proj forKey:@"Proj"];
[tempProjectDictionaryArray setObject:project.desc forKey:@"Desc"];

但将

nil

值替换为

[NSNull null]

，因此您可以删除这些值 从字典里

NSArray *keysForNullValues = [tempProjectDictionaryArray allKeysForObject:[NSNull null]];
[tempProjectDictionaryArray removeObjectsForKeys:keysForNullValues];

---

可能是您的代码必须是：

    for (ProjectList *projectList in fetchedObjects) {

        NSMutableDictionary *tempProjectDictionaryArray = [[ NSMutableDictionary alloc] init];

        [tempProjectDictionaryArray setObject:projectList.proj forKey:@"Proj"]; // this is where the ap dies
        [tempProjectDictionaryArray setObject:projectList.desc forKey:@"Desc"];

        [projectDictionaryArray addObject:tempProjectDictionaryArray];
    }

---

其中project.proj由projectList.proj（也用于.desc）更改。

什么包含project.proj？错误是说不能为零？当您在使用

@“项目”

时，您的实体名称是错误的。它应该是

ProjectList

。如果有几个值，有没有办法检查所有值？或者每一行都必须是这样的吗？坏的命名法的例外。我有另一个名为ProjectList的coredataobject。。你的回答确实正确。谢谢你的帮助