Question

似乎对{5}的NSPersistentStoreCoordinator方法进行了一些修改。我试图获得一个预先填充的数据库...它似乎没有工作，没有崩溃，但似乎没有任何数据...任何建议？

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

    NSURL *storePath = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"DataModel.sqlite"];

    /*
     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:[storePath absoluteString]]) {
        NSString *defaultStorePath = [[NSBundle mainBundle] pathForResource:@"DataModel" ofType:@"sqlite"];
        if (defaultStorePath) {
            [fileManager copyItemAtPath:defaultStorePath toPath:[storePath absoluteString] error:NULL];
        }
    }


    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"DataModel.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;
}

Answer 1

问题出在applicationDocumentsDirectory方法中，它提供了错误的绝对字符串。这不是真的错，但不适合NSFileManager类。

解决方案很简单。您需要编写另一种我称为applicationDocumentsDirectory2的方法。

首先，转到AppDelegate的头文件并声明方法：

- (NSString *)applicationDocumentsDirectory2;

现在，转到.m文件，并定义一个方法：

- (NSString *)applicationDocumentsDirectory2 {

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
    return basePath;
}

最后，只需将persistentStoreCoordinator方法更改为：

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (__persistentStoreCoordinator != nil)
    {
        return __persistentStoreCoordinator;
    }
    NSError *error = nil;

   NSString *storePath = [[self applicationDocumentsDirectory2] stringByAppendingPathComponent: @"DataModel.sqlite"];

    /*
     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:storePath]) {
        NSString *defaultStorePath = [[NSBundle mainBundle] pathForResource:@"DataModel" ofType:@"sqlite"];
        if (defaultStorePath) {
            if(![fileManager copyItemAtPath:defaultStorePath toPath:storePath error:&error]) {
                NSLog(@"Unresolved error %@, %@", error, [error userInfo]);


            }
        } 
    }


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

    __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;

}

就是这样！：）

在iOS 5中预填充核心数据

1 个答案: