ios - persistenceStoreCoordinator 有什么问题？

Question

谁能告诉我下面的代码有什么问题吗？ 它总是在包含“addPersistentStoreWithType”的行处崩溃。

欢迎任何建议。

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it.
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }

    // Create the coordinator and store
     _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Core_Data.sqlite"];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    if (![fileManager fileExistsAtPath:[storeURL path]]) {
        NSURL *defaultStoreURL=[[NSBundle mainBundle] URLForResource:@"Core_Data" withExtension:@"sqlite"];

        if (defaultStoreURL) {
            // By default we use what is in the bundle read-only.
            storeURL=defaultStoreURL;
            _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
            if (![fileManager fileExistsAtPath:[storeURL path]])
                NSLog(@"RO-DB NOT FOUND");
            else NSLog(@"RO-DB FOUND");


            NSError *error = nil;
            if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
                                                           configuration:nil
                                                                     URL:storeURL
                                                                 options:@{NSSQLitePragmasOption:@{ @"journal_mode":@"DELETE" },
                                                                           NSReadOnlyPersistentStoreOption:[NSNumber numberWithBool:YES]}
                                                                   error:&error]) {
                NSLog(@"RO-DB NOT OPENED");
            }

            return _persistentStoreCoordinator;
       }
    }

    NSError *error = nil;
    NSString *failureReason = @"There was an error creating or loading the application's saved data.";
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
        // Report any error we got.
        NSMutableDictionary *dict = [NSMutableDictionary dictionary];
        dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application's saved data";
        dict[NSLocalizedFailureReasonErrorKey] = failureReason;
        dict[NSUnderlyingErrorKey] = error;
        error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
        // Replace this 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();
    }

    return _persistentStoreCoordinator;
}

其余的代码只不过是 Xcode 在使用具有核心数据的单 View 模板构建新项目时生成的代码。

Answer 1

您不能添加 bundle 中的读写存储。该包是只读的。

相反，先将 sqlite 文件复制到文档目录，然后使用该 URL 将商店添加到商店协调器。

我认为 journal_mode "delete"和 NSReadOnlyPersistentStoreOption 不兼容。 (无论如何，这似乎没有任何意义。)也许 journal_mode“关闭”或没有 journal_mode 选项更有希望。