Question

使用内容初始化Core Data数据库的最佳方法是什么。我的iPhone应用程序将有一个带有产品（数据和图像）的静态数据库。如何/在哪里存储图像，如何预先填充数据库？

Answer 1

这是我做的：

在iPhone应用程序内创建数据库
我在XCode中创建了模型并对数据库进行了查询（这会创建数据库）
我的静态数据是CSV文件
使用Ruby脚本读取CSV文件
使用ruby gem sqlite3将数据插入数据库
复制回项目

替代：

将包含数据的CSV / XML文件存储在应用程序中
在启动时解析并创建NSMAnagedObjects

工具/资源：

Base用于编辑/查看sqlite3数据库的软件

数据库位置：我担心我不记得它，但是当你使用模拟器时，你的应用程序将被构建并复制到一个目录中。我认为你的应用程序的路径将是这样的。数据库取决于它的设置方式通常位于Documents文件夹中。

~User/Library/Application Settings/iOS Simulator/<version>/<app id>/

Answer 2

参考官方Apple文档提供了一种将数据预填充到Core Data中的方法： Core Data Books

在我自己的应用程序中，我用这个替换了AppDeledate中的'NSPersistentStoreCoordinator'函数：

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

NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreDataBooks.CDBStore"];

/*
 Set up the store.
 For the sake of illustration, provide a pre-populated default store.
 */
NSFileManager *fileManager = [NSFileManager defaultManager];
// If the expected store doesn't exist, copy the default store.
if (![fileManager fileExistsAtPath:[storeURL path]]) {
    NSURL *defaultStoreURL = [[NSBundle mainBundle] URLForResource:@"CoreDataBooks" withExtension:@"CDBStore"];
    if (defaultStoreURL) {
        [fileManager copyItemAtURL:defaultStoreURL toURL:storeURL error:NULL];
    }
}

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

NSError *error;
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options 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. 

     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.


     If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.

     If you encounter schema incompatibility errors during development, you can reduce their frequency by:
     * Simply deleting the existing store:
     [[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil]

     * Performing automatic lightweight migration by passing the following dictionary as the options parameter:
     @{NSMigratePersistentStoresAutomaticallyOption:@YES, NSInferMappingModelAutomaticallyOption:@YES}

     Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.

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

return _persistentStoreCoordinator;

}

希望这有效，祝你好运！

iPhone核心数据预设

2 个答案: