iOS - 当新数据发布到 NSMutableArray 时触发通知？

Question

我已经在我的服务器上设置了推送通知，一切都运行良好。 例如我可以随时向所有用户发送通知(因为所有设备 token 都存储到我的数据库中)。也就是说，当应用程序中镜像的服务器上的数据更新时(例如当新消息发布到服务器)？

更具体地说:请参阅下面的代码，我用它在表格 View 中显示所有收到的消息。如何才能使登录用户在 self.messages 更新时收到通知？

ViewController.m

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *PointsTableIdentifier = @"MyMessagesCell";

    MyMessagesCell *cell = (MyMessagesCell *)[tableView dequeueReusableCellWithIdentifier:PointsTableIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"MyMessagesCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];

    }


    NSDictionary *receivedSubjectLine = [self.messages objectAtIndex:indexPath.row];

    NSString *messageSubject = [receivedSubjectLine objectForKey:@"node_title"];


    [cell.subjectLine setText:messageSubject];



    NSDictionary *fromUser = [self.messages objectAtIndex:indexPath.row];

    NSString *userName = [fromUser objectForKey:@"name"];

    [cell.senderName setText:userName];



    NSDictionary *receivedBody = [self.messages objectAtIndex:indexPath.row];

    NSString *messageBody = [receivedBody objectForKey:@"body"];

    [cell.fullMessage setText:messageBody];


    NSDictionary *receivedTime = [self.messages objectAtIndex:indexPath.row];

    NSString *timeStamp = [receivedTime objectForKey:@"swaptime"];

        NSLog(@"The timestamp is %@", timeStamp);

    [cell.swapTime setText:timeStamp];

    return cell;

}

Answer 1

我的应用程序中有一个聊天不使用Web Socket(我们没有时间实现它)，所以我们要做的是使用通知中心刷新UITableView。

在 AppDelegate 中我有以下代码:

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"reloadTheTable" object:nil];
}

然后在我的聊天类中，我有以下代码在 viewDidLoad 中注册通知:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reloadTable:) name:@"reloadTheTable" object:nil];

然后选择器调用服务器并刷新显示的数据:

- (void)reloadTable:(NSNotification *)notification
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [self checkJson]; //This function loads the data and when it finish calls another method call loadTable
}

- (void)loadTable {
    [_tvTable reloadData]; //this simply reload your UITableView
}

我还使用此技术在应用程序进入前台时重新加载:

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    [[NSNotificationCenter defaultCenter] postNotificationName:@"reloadTheTable" object:nil];
}

希望这对您有帮助。