ios - NSPersistentStoreCoordinator在ios中没有持久化存储(Schema不匹配或迁移失败)核心数据iOS

Question

我添加了新版本的数据模型。我在新版本中添加了新字段。还将当前模型版本设置为新创建的版本。

代码更新:

 - (NSManagedObjectModel *)managedObjectModel
     {
         if (_managedObjectModel != nil) {
             return _managedObjectModel;
          }
      NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"PPUSFAModel" withExtension:@"momd"];

       //I earlier was PPUSFAModel 16, i added new model version PPUSFAModel 17. 

     _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
            return _managedObjectModel;
        }
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:SQLITENAME];

    NSError *error = nil;
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES],   NSMigratePersistentStoresAutomaticallyOption,
                             [NSNumber numberWithBool:YES],  NSInferMappingModelAutomaticallyOption, nil];

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

    return _persistentStoreCoordinator;
}

它一直有效，直到添加了一些属性，但在某些时候我在以下代码处崩溃了

- (void)saveContext
{

    __block NSError *error = nil;
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;

    [managedObjectContext performBlockAndWait:^{

        if (managedObjectContext != nil && _persistentStoreCoordinator != 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.
                // DLog(@"Unresolved error %@, %@", error, [error userInfo]);
                //abort();
            }
        } }];
}

这是崩溃的截图:

当我通过从设备上删除较早的应用程序进行安装时，它可以正常工作，但在现有版本上更新应用程序时会崩溃。

//如果我不小心在旧模型版本而不是新版本中添加了字段，该如何解决？

任何帮助将不胜感激。

Answer 1

请确保您已更新模型“当前版本”。 Update "Current Version" in .xcdatamodel -> File Inspector -> Model version

然后转到“AppDelegate.swift”文件并添加以下代码:

let options = [NSMigratePersistentStoresAutomaticallyOption: true, NSInferMappingModelAutomaticallyOption: true]

然后将“选项”应用到参数“选项”的以下代码中:

try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: options)

代码如下所示: image