小编Dan*_*tín的帖子

我已经完成了斯坦福大学的课程，并按照讲座中的步骤设置了我的第一个应用程序和核心数据。大约是这样（我现在将代码转移到应用程序委托中）：

- (void)setupFetchedResultsController
{
    NSError *error = nil;
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"MainCategory"];
    request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"position" ascending:YES]];
    [self.budgetDatabase.managedObjectContext executeFetchRequest:request error:&error];

    self.fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:request
                                                                       managedObjectContext:self.budgetDatabase.managedObjectContext
                                                                         sectionNameKeyPath:nil
                                                                                  cacheName:nil];
}

-(void)useDocument
{
    if(![[NSFileManager defaultManager]fileExistsAtPath:[self.budgetDatabase.fileURL path]]){
        [self.budgetDatabase saveToURL:self.budgetDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
            [self setupFetchedResultsController];
        }];
    } else if (self.budgetDatabase.documentState == UIDocumentStateClosed){
        [self.budgetDatabase openWithCompletionHandler:^(BOOL success){
            [self setupFetchedResultsController];
        }];
    } else if (self.budgetDatabase.documentState == UIDocumentStateNormal){
        [self setupFetchedResultsController];
    }
}

- (void)viewWillAppear:(BOOL)animated
{
    //Initialize database
    [super viewWillAppear:animated];
    if(!self.budgetDatabase){
        NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentationDirectory …

我想检测UIDeviceOrientationFaceDown.我怎样才能做到这一点？？？实际上我想在我的iphone面朝下平面时执行一些操作.这怎么可能？？？请帮助我这样做.

我有这个代码,但不知道在何处以及如何应用此代码

 [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];

 BOOL getOrientationUpdates = [[UIDevice currentDevice] isGeneratingDeviceOrientationNotifications];
   NSLog(@"will receive orientation notifications: %@", getOrientationUpdates?@"YES":@"NO");

  [[NSNotificationCenter defaultCenter] addObserver:self
                                     selector:@selector(orientationChanged:)
                                         name:UIDeviceOrientationDidChangeNotification
                                       object:nil];

如果有任何教程,请建议我

在此先感谢,非常欢迎您的宝贵帮助和建议.