无法在IOS5中使用核心数据库

Question

I am working with a core database, it is working in IOS 6 but when I trying to test it on IOS 5. It does not do anything. Let me explain what I'm doing.

First I do this in my viewWillAppear.

- (void)viewWillAppear:(BOOL)animated
{
    NSLog(@"view appeared");
    [super viewWillAppear:animated];
    if (!self.genkDatabase) {
        NSLog(@"comes to here");
        NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
        url = [url URLByAppendingPathComponent:@"Default appGenk Database2"];
        // url is now "<Documents Directory>/Default Photo Database"
        self.genkDatabase = [[UIManagedDocument alloc] initWithFileURL:url]; // setter will create this for us on disk
        NSLog(@"database created on disk");
    }

}

Then it comes in the UseDocument method.

- (void)useDocument
{
    NSLog(@"Comses in the use document");
    if (![[NSFileManager defaultManager] fileExistsAtPath:[self.genkDatabase.fileURL path]]) {
        // does not exist on disk, so create it
        [self.genkDatabase saveToURL:self.genkDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
            NSLog(@"create");
            [self setupFetchedResultsController];
           [self fetchGenkDataIntoDocument:self.genkDatabase];

        }];
    } else if (self.genkDatabase.documentState == UIDocumentStateClosed) {
        NSLog(@"closed news");
        // exists on disk, but we need to open it
        [self.genkDatabase openWithCompletionHandler:^(BOOL success) {
            [self setupFetchedResultsController];
        }];
    } else if (self.genkDatabase.documentState == UIDocumentStateNormal) {
        NSLog(@"normal");
        // already open and ready to use
        [self setupFetchedResultsController];
    }

}

And finally it goes into the setDatabase Method.

- (void)setGenkDatabase:(UIManagedDocument *)genkDatabase
{
    if (_genkDatabase != genkDatabase) {
        _genkDatabase = genkDatabase;
        [self useDocument];
    }
    NSLog(@"Comes in the setdatabase methode.");
}

Doing all this gives the following log.

2012-10-22 10:42:47.444 RacingGenk[4786:c07] view appeared
2012-10-22 10:42:47.445 RacingGenk[4786:c07] comes to here
2012-10-22 10:42:47.459 RacingGenk[4786:c07] Comses in the use document
2012-10-22 10:42:47.460 RacingGenk[4786:c07] Comes in the setdatabase methode.
2012-10-22 10:42:47.461 RacingGenk[4786:c07] database created on disk

Like you can see it does not print the create log in my use document. So it isn't able to execute the method FetchDataIntoDocument .

Can anybody help me with this problem. I am searching at this problem for ages for now.

Many thanks in advace.

Stef

Answer 1

Are you testing with the simulator or on the device? The simulator is case-insensitive - the device is case-sensitive on file access, remember that!

But beside from that the documentation for NSFileManager recommends not checking to see if files exist, and instead just trying to read the file and handle any errors gracefully (eg file not found error). So just try loading the file instead of checking to see if it exists.

And i don't see any file extension for your database file! It just states ""Default appGenk Database2". Is this already the file name or jut another subdirectory so far?

EDIT:

You can try the following code:

- (void) setupStore {
    NSString* storePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"mydatabase.sqlite"];

    // Set up the store.
    NSFileManager* fileManager = [NSFileManager defaultManager];
    // If the expected store doesn't exist, create one.
    if (![fileManager fileExistsAtPath: storePath]) {
        // create your store here!
    }
}


- (NSString*) applicationDocumentsDirectory {
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}

"mydatabase.sqlite" is the name of the database-file you expect to be present in your documents directory.

If you would like to see a full-fledged example on how to set-up a core data persistent store you could check out apples own iPhoneCoreDataRecipes example. Just take a look at the

RecipesAppDelegate.m

implementation.