ios – 如何重新创建不受更改.xcdatamodeld影响的persistentStore

2023年12月12日 203次阅读

我想重新创建(删除和创建)persistentStore不受更改.xcdatamodeld的影响.

我在AppDelegate中编写了一个代码persistentStoreCoordinator,如下所示：

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }

    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"myproject.sqlite"];

    // delete if database exists
    NSError *error = nil;
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {

        // if .xcdatamodeld is changed, fail and in here...
        // if not changed, recreate success. all data removed from database

        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }
    NSArray *stores = [_persistentStoreCoordinator persistentStores];
    for (NSPersistentStore *store in stores) {
        [_persistentStoreCoordinator removePersistentStore:store error:nil];
        [[NSFileManager defaultManager] removeItemAtPath:store.URL.path error:nil];
    }

    // newly create database
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return _persistentStoreCoordinator;
}

当我对.xcdatamodeld进行更改(例如,向实体添加新列)和重新启动模拟器时,首先失败的是addPersistentStoreWithType并且log表示

Unresolved error Error Domain=NSCocoaErrorDomain Code=134100 
The operation couldn’t be completed. (Cocoa error 134100.)

我怎样才能做到这一点？

最佳答案 以下代码对我来说似乎很有用.

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }

    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"myproject.sqlite"];

    // delete database if exists
    [[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:nil];

    // create database
    NSError *error = nil;
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return _persistentStoreCoordinator;
}

我在下面检查过(在设备和模拟器中)：

>首次启动时,应创建数据库
>编辑.xcdatamodeld(添加/编辑/删除列或实体)然后重新启动,应重新创建数据库

谢谢你的建议.

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