managedObjectModel 为 nil（仅在 WatchApp 中）

Question

我正在为 Apple Watch 更新应用程序这个应用程序使用 coredata ，所以我创建了一个框架来管理核心数据堆栈！当我在设备或模拟器上运行该应用程序时，该应用程序工作正常，但是当我在 Apple Watch 模拟器上运行它时，该应用程序崩溃并显示此日志

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Cannot create an NSPersistentStoreCoordinator with a nil model'

问题似乎出在 managedObjectModel 上，如果我记录它

NSLog(@"managedObjectModel %@", _managedObjectModel);

日志返回

managedObjectModel (null)

框架中的代码似乎是正确的，实际上主应用程序运行完美

反正这是框架的内容

#import "DataAccess.h"

@implementation DataAccess

@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;


+ (instancetype)sharedInstance
{
    static DataAccess *sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[DataAccess alloc] init];
        // Do any other initialisation stuff here
    });
    return sharedInstance;
}

- (void)saveContext
{
    NSError *error = nil;
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
    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.
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }
    }
}



#pragma mark - Core Data stack

// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
- (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 from the application's model.
- (NSManagedObjectModel *)managedObjectModel
{
    if (_managedObjectModel != nil) {

        NSLog(@"managedObjectModel %@", _managedObjectModel);

        return _managedObjectModel;

    }
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"MyApp" withExtension:@"momd"];
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

    NSLog(@"managedObjectModel %@", _managedObjectModel);


    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 = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"TMM.sqlite"];
    //NSURL *storeURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory  inDomains:NSAllDomainsMask] lastObject];
//    storeURL = [storeURL URLByAppendingPathComponent:@"db.sqlite"];

    NSURL *storeURL = [[NSFileManager defaultManager] containerURLForSecurityApplicationGroupIdentifier:@"group.ragazzetto.MyApp.Documents"];
    storeURL = [storeURL URLByAppendingPathComponent:@"MyApp.sqlite"];

    NSError *error = nil;
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {

        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return _persistentStoreCoordinator;
}
#pragma mark - Application's Documents directory

// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}


@end

问题出在哪里？

感谢您的帮助

Answer 1

当您编写 iOS 应用程序扩展时——包括所有当前的 WatchKit 应用程序——您正在创建一个单独的可执行文件，它有自己的包。应用中的资源不一定在扩展中可用，反之亦然。所以当你这样做时：

NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"MyApp" withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

当运行在 WatchKit 应用程序中时，URL 与在包含应用程序中的运行不同。该错误告诉您 WatchKit 应用程序的 URL 无效，即 WatchKit 应用程序的捆绑包中没有模型文件。

简单的解决方法是将模型包含在 WatchKit 包中。通过以下方式执行此操作：

选择Xcode中的模型文件
正在打开 Xcode window
查看 "target membership" 部分。确保选择了您的 WatchKit 目标。

这应该可行，但意味着您有模型文件的两个副本。更好的方法是将模型文件放入两个目标都使用的共享框架中。这有点复杂，但稍微搜索一下就会找到详细的步骤。

managedObjectModel 为 nil（仅在 WatchApp 中）

managedObjectModel in nil ( only in WatchApp )

frameworks

core-data

objective-c

ios

watchapp