“无法加载NSManagedObjectModel。 nil是非法的URL参数“ [英] "Cannot load NSManagedObjectModel. nil is an illegal URL parameter"

问题描述

我想从AppDelegate获取托管对象上下文，但应用程序崩溃后，我把两行代码进入方法，即使我没有别的，并在调试区域有一个消息：CoreData：无法加载NSManagedObjectModel。nil是一个非法的网址参数...

I want to get the managed object context from AppDelegate, but the app crashed after I put the two lines of code into the method even I did nothing else, and there was a message in debug area:"CoreData: Cannot load NSManagedObjectModel. nil is an illegal URL parameter..."

在我的方法中添加的代码：

The code added in my method:

AppDelegate *delegate = [UIApplication sharedApplication].delegate;
NSManagedObjectContext *managedObjectContext = delegate.managedObjectContext;

AppDelegate中的-managedObjectModel方法：

-managedObjectModel method in AppDelegate:

- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
    return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"FoodPin" withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}

和-managedObjectContext方法：

and the -managedObjectContext method:

- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
    return _managedObjectContext;
}

NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
    return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc]initWithConcurrencyType:NSPrivateQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}

FoodPin是我的专案名称这里有什么问题？我是iPhone新手（特别是Core Data）。

"FoodPin" is my project name.So what's wrong here?I'm new to iPhone programming (Core Data in particular).

任何人都可以帮我吗？

感谢...

推荐答案

问题是这一行：

NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"FoodPin" withExtension:@"momd"];

modelURL 是 nil 意味着系统找不到资源 FoodPin.momd 。

modelURL is nil meaning that the system couldn't find the resource FoodPin.momd.

确保您的项目中有一个Core Data模型名为 FoodPin 。它将在项目导航器中显示为 FoodPin.xcdatamodeld 。

Make sure you have a Core Data model in your project named FoodPin. It will appear as FoodPin.xcdatamodeld in the Project Navigator.

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