Question

我的uitableview调用reloaddata当设备的方向发生变化时（因为显示的单元格数量发生了变化，所以在布局子视图中调用，据我从文档中可以理解），但这对我来说是有问题的，因为我在后台执行下载，我不希望突然出现一些文件。有没有办法停止默认行为，让我在需要时手动重新加载？

编辑：我会尝试更好地解释。在我的tableview的顶部，我有一个名为“sync”的按钮，它从服务器启动一个同步请求，这个同步请求首先得到一个JSON对象，它保存我想在tableview中显示的信息，但每个uitableview项代表我从互联网上下载的文件。

当文件正在下载时，我在屏幕上有一个活动指示器，只有当文件完成下载时我才想重新加载表格。问题是，UITableview会在用户更改方向时自动调用reloaddata，因此在下载的文件下载完成之前，单元格会填充json中的信息。

代码：

@implementation BIDManageFilesViewController

- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(newDataFinishedDownloading) name:kBIDContentManagerContentDidChangeNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(newDataStartedDownloading:) name:kBIDContentManagerStartedDownloadingContent object:nil];
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(contentAlreadyUpToDate) name:kBIDContentUpToDate object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(contentStartingSync) name:kBIDContentStartingSync object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(contentEndingSync) name:kBIDContentEndingSync object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(singleDownloadFinished) name:kBIDFinishedDownloadingSingleContent object:nil];
    self.navigationController.navigationBarHidden = NO;
    UIBarButtonItem *leftButton = [[UIBarButtonItem alloc] initWithTitle:@"Sync"
                                                                    style:UIBarButtonItemStyleDone target:self action:@selector(Sync)];
    self.navigationItem.leftBarButtonItem = leftButton;
    UIBarButtonItem *rightButton = [[UIBarButtonItem alloc] initWithTitle:@"Display Mode"
                                                                   style:UIBarButtonItemStyleDone target:self action:@selector(dismissSelf)];
    self.navigationItem.rightBarButtonItem = rightButton;

    self.navigationItem.title = @"Content Manager";
    self.navigationBar = [[UINavigationBar alloc] initWithFrame:CGRectZero];
    [self.view addSubview:_navigationBar];
    [self.navigationBar pushNavigationItem:self.navigationItem animated:NO];

}
-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationFade];

}
-(void)layoutNavigationBar{
    if([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortrait || [[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortraitUpsideDown)
    {
    self.navigationBar.frame = CGRectMake(0, self.tableView.contentOffset.y, self.view.frame.size.width, self.topLayoutGuide.length + 44);
    }
    else
    {
        self.navigationBar.frame = CGRectMake(0, self.tableView.contentOffset.y, self.view.frame.size.height, self.topLayoutGuide.length + 44);
    }
    NSLog(@"width: %f", self.view.frame.size.width);
    NSLog(@"height: %f", self.view.frame.size.height);
    self.tableView.contentInset = UIEdgeInsetsMake(self.navigationBar.frame.size.height, 0, 0, 0);
}

-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
    //no need to call super
    [self layoutNavigationBar];
}
-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    [self layoutNavigationBar];
    [super willRotateToInterfaceOrientation:toInterfaceOrientation duration:duration];

}
-(void)viewDidLayoutSubviews{
    [super viewDidLayoutSubviews];
    [self layoutNavigationBar];
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}




/*
#pragma mark - Navigation

// In a story board-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}

 */
-(void)viewDidDisappear:(BOOL)animated
{
    [super viewDidDisappear:animated];
    self.navigationController.navigationBarHidden = YES;

}
-(void)newDataStartedDownloading: (NSNotification *)notif
{
    self.hud = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
    _hud.labelText = @"Downloading...";
    _hud.detailsLabelText = [NSString stringWithFormat:@"1/%@",[notif.userInfo objectForKey:@"downloadFileNumber"]];

}
-(void)singleDownloadFinished
{
    NSString *currentText = _hud.detailsLabelText;
    NSArray *subStrings = [currentText componentsSeparatedByString:@"/"];
    NSInteger downloadsPlusOne = [[subStrings objectAtIndex:0] integerValue]+1;
    NSString *newTextForLabel = [NSString stringWithFormat:@"%d/%@", downloadsPlusOne, [subStrings objectAtIndex:1]];
    _hud.detailsLabelText = newTextForLabel;
}
-(void)newDataFinishedDownloading
{
    _thereIsNewInfo = TRUE;
    [MBProgressHUD hideHUDForView:self.view animated:YES];
    [self.tableView reloadData];
    [[NSNotificationCenter defaultCenter] postNotificationName:kBIDnewDownloadedContentReadyToBeDispayedNotification object:nil userInfo:nil];

}
-(void)contentAlreadyUpToDate
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sync Alert"
                                                    message:@"Files Are Already Up To Date"
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles: nil];
    [alert show];

}
-(void)contentStartingSync
{
    MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
    hud.labelText = @"Syncing...";

}
-(void)contentEndingSync
{
     [MBProgressHUD hideHUDForView:self.view animated:YES];

}
-(void)Sync
{
    [AppDelegate.appContentManager downloadContent];
}
-(void)dismissSelf
{
    if (![AppDelegate.appContentManager subsetArrayFromFileArrayWithNonVidContentThatShouldDisplay] && ![AppDelegate.appContentManager subsetArrayFromFileArrayWithVideoContentThatShouldDisplay]) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No Files to Display"
                                                        message:@"Please update or enable content"
                                                       delegate:nil
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles: nil];
        [alert show];
        return;
    }
    else if ([AppDelegate.appContentManager subsetArrayFromFileArrayWithNonVidContentThatShouldDisplay])
    {
        [self dismissViewControllerAnimated:YES completion:Nil];

    }
    else
    {
    [self performSegueWithIdentifier:@"goToVideos" sender:self];
    }
}
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"goToVideos"])
    {
        ((BIDViewController *)segue.destinationViewController).stackedByManager = TRUE;
    }

}

@end

Answer 1

没有必要在方向更改时重新加载数据，但是如果要重新加载表，请尝试在完成后台下载后调用[myTable reloadData]，并且只有在方向已更改时（您可以在方向上设置bool）。变化）。

阻止UITableView重新加载方向更改数据

1 个答案: