iphone - 核心数据崩溃 : [__NSArrayM insertObject:atIndex:]: object cannot be nil

Question

我正在尝试在我的应用程序中实现 CoreData 以存储小型数据库。

这里是我的实现:

AppDelegate.h

#import <UIKit/UIKit.h>
#import "FavoritosViewController.h"
#import <CoreData/CoreData.h>

@interface XXX : NSObject <UIApplicationDelegate>{

    NSManagedObjectModel *managedObjectModel;
    NSManagedObjectContext *managedObjectContext;       
    NSPersistentStoreCoordinator *persistentStoreCoordinator;



}
- (NSString *)applicationDocumentsDirectory;

@property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel;
@property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext;
@property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;

@end

AppDelegate.m

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{

    FavoritosViewController *global=[[FavoritosViewController alloc]init];

    global.managedObjectContext=[self managedObjectContext];

    .
    .
    .
    }

        - (void)applicationWillTerminate:(UIApplication *)application
    {
        NSError *error = nil;
        if (managedObjectContext != nil) {
            if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
                /*
                 Replace this implementation with code to handle the error appropriately.

                 abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
                 */
                NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
                abort();
            } 
        }

    }

- (NSManagedObjectContext *) managedObjectContext {

    if (managedObjectContext != nil) {
        return managedObjectContext;
    }

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


/**
 Returns the managed object model for the application.
 If the model doesn't already exist, it is created by merging all of the models found in the application bundle.
 */
- (NSManagedObjectModel *)managedObjectModel {

    if (managedObjectModel != nil) {
        return managedObjectModel;
    }
    managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];    
    return managedObjectModel;
}


/**
 Returns the persistent store coordinator for the application.
 If the coordinator doesn't already exist, it is created and the application's store added to it.
 */
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

    if (persistentStoreCoordinator != nil) {
        return persistentStoreCoordinator;
    }

    NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"FavoritosDatabase.sqlite"]];

    NSError *error = nil;
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error]) {
        /*
         Replace this implementation with code to handle the error appropriately.

         abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.

         Typical reasons for an error here include:
         * The persistent store is not accessible
         * The schema for the persistent store is incompatible with current managed object model
         Check the error message to determine what the actual problem was.
         */
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }    

    return persistentStoreCoordinator;
}




- (NSString *)applicationDocumentsDirectory {
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}

我还有一个带有“事件”实体的 xcdatamodeld 及其属性，以及来自它的 Event.h、Event.m。

在 FavoritosViewController 中我也有所有的方法，但问题先于此。

它出现在

managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];    

应用程序崩溃并显示如下:

* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[__NSArrayM insertObject:atIndex:]: object cannot be nil'

有什么想法吗？？？谢谢!!!

Answer 1

当我的代码运行 [NSManagedObjectModel mergedModelFromBundles:nil] 时，我遇到了类似的问题和相同的错误消息。这是在 xCode 意外崩溃后发生的。即使当我恢复到我的代码的已知良好版本时，我仍然有同样的错误，这是由于某种损坏造成的。

经过多次试验，我能够通过退出 Xcode 和 iPhone 模拟器，然后删除以下目录中的所有文件来解决问题:

$ cd /Users/john/Library/Developer/Xcode/DerivedData

$ rm -R -f ./(folder corresponding to my project name)

$ cd /Users/john/Library/Application Support/iPhone Simulator/5.0/Applications

$ rm -R *

这能够清除损坏的临时文件和模拟器的状态，并且错误消失了。