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我有一个表格视图控制器和一个由单元格和导航栏连接的详细视图控制器。在详细视图控制器中是一个倒数计时器，时间间隔由用户指定。它在第一次单击单元格以获取详细视图控制器时起作用，但是当点击并重新点击同一单元格时，它会重新开始。我知道为什么，但我不知道如何解决它（它在这篇文章的末尾）。这是我的代码：

任务 = 放在表格视图单元格中的对象

taskArray = 未完成的任务对象数组

completedArray = 已完成任务对象的数组

表视图控制器.m

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
 cellSubclassCell *cell = [tableView dequeueReusableCellWithIdentifier:@"UITableViewCell"];
    if (!cell)
        cell = [[cellSubclassCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"UITableViewCell"];

    if([indexPath section] == 0){
    cell.textLabel.text = [[[self.taskArray objectAtIndex:[indexPath row]] taskName] uppercaseString];

    cell.imageView.image = [UIImage imageNamed:@"unchecked.png"];
        cell.imageView.highlightedImage = [UIImage imageNamed:@"uncheckedhighlighted.png"];
        [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
        [cell setBackgroundColor:[UIColor colorWithRed:236.0/255 green:240.0/255 blue:241.0/255 alpha:1.0f]];
        cell.textLabel.textColor = baseColor;

        NSString *detailText = [[self.taskArray objectAtIndex:[indexPath row]] timeIntervalString];
        cell.detailTextLabel.text = detailText;
               [[cell detailTextLabel] setFont:[UIFont fontWithName:@"Avenir-Black" size:12]];
        [[cell textLabel] setFont:[UIFont fontWithName:@"AvenirNext-DemiBold" size:16]];
[cell.contentView setAlpha:1];
    } else if ([indexPath section] == 1) {
    cell.textLabel.text = [[[self.completedArray objectAtIndex:[indexPath row]] taskName] uppercaseString];

     cell.imageView.image = [UIImage imageNamed:@"checked.png"];
        [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
        [cell setBackgroundColor:[UIColor colorWithRed:236.0/255 green:240.0/255 blue:241.0/255 alpha:1.0f]];
        cell.textLabel.textColor = baseColor;
        NSString *detailText = [[self.completedArray objectAtIndex:[indexPath row]] timeIntervalString];
        cell.detailTextLabel.text = detailText;
        [[cell detailTextLabel] setFont:[UIFont fontWithName:@"Avenir-Black" size:12]];
        [[cell textLabel] setFont:[UIFont fontWithName:@"AvenirNext-DemiBold" size:16]];
        [cell.contentView setAlpha:0.5];
    }
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handlechecking:)];
    //cell.contentView
    [cell.imageView addGestureRecognizer:tap];
    cell.imageView.userInteractionEnabled = YES;
    return cell;
    }
-(void)handlechecking:(UITapGestureRecognizer *)t{

        CGPoint tapLocation = [t locationInView:self.tableView];
        NSIndexPath *tappedIndexPath = [self.tableView indexPathForRowAtPoint:tapLocation];
        NSIndexPath *newIndexPath = nil;

        if (tappedIndexPath.section == 0) {

            NSUInteger newRowIndex = self.completedArray.count;
            [self.completedArray addObject:[self.taskArray objectAtIndex:tappedIndexPath.row]];
            [self.taskArray removeObject:[self.taskArray objectAtIndex:tappedIndexPath.row]];
            newIndexPath = [NSIndexPath indexPathForRow:newRowIndex inSection:1];

        } else {

            NSUInteger newRowIndex = self.taskArray.count;
            [self.taskArray addObject:[self.completedArray objectAtIndex:tappedIndexPath.row]];
            [self.completedArray removeObject:[self.completedArray objectAtIndex:tappedIndexPath.row]];
            newIndexPath = [NSIndexPath indexPathForRow:newRowIndex inSection:0];
        }
        [self.tableView beginUpdates];
        [self.tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
        [self.tableView deleteRowsAtIndexPaths:@[tappedIndexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
        [self.tableView endUpdates];

}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    NSInteger num = 0;
    if (section == 0) {
        num = self.taskArray.count;
    } else {
        num = self.completedArray.count;
    }
    return num;
}
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    Tasks *task = [[Tasks alloc]init];
    if (indexPath.section == 0){
    task.taskName = [[self.taskArray objectAtIndex:[indexPath row]] taskName];
        task.timeInterval = [[self.taskArray objectAtIndex:[indexPath row]] timeInterval];
    task.dateCreated = [[self.taskArray objectAtIndex:[indexPath row]] dateCreated];
    } else if (indexPath.section == 1){
        task.taskName = [[self.completedArray objectAtIndex:[indexPath row]] taskName];
        task.timeInterval = [[self.completedArray objectAtIndex:[indexPath row]] timeInterval];
        task.dateCreated = [[self.completedArray objectAtIndex:[indexPath row]] dateCreated];
    }
    DetailViewController *dvc = [[DetailViewController alloc]init];
    [dvc setTestTask:task];
    [[self navigationController] pushViewController:dvc animated:YES];
}

细节视图控制器.m

-(IBAction)startTimer:(id)sender{
    [sender setHidden:YES];
    [pauseButton setHidden:NO];
    [continueButton setHidden:NO];
        gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
        self.date1 = [NSDate dateWithTimeInterval:[testTask timeInterval] sinceDate:[NSDate date]];

        timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timerAction:) userInfo:nil repeats:YES];
    [timer fire];

}
-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];

    [timerLabel setFont:[UIFont fontWithName:@"BebasNeue" size:60]];
    [[self navigationItem] setTitle:[testTask taskName]];
    if (startButton.hidden == NO){
        [pauseButton setHidden:YES];
        [continueButton setHidden:YES];
    } else {
        [pauseButton setHidden:NO];
        [continueButton setHidden:NO];
    }
      timeRemaining = [NSString stringWithFormat:@"%02d:%02d:%02d", [components hour], [components minute], [components second]];
    timerLabel.text = timeRemaining;
    [timerLabel setNeedsDisplay];
    [self.view setNeedsDisplay];
}
-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];

    [testTask setTaskName:[testTask taskName]];
    [testTask setTimeInterval:[testTask timeInterval]];

}
-(void)timerAction:(NSTimer *)t{
     NSDate *now = [NSDate date];
    components = [gregorianCalendar components:NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit  fromDate:now toDate:self.date1 options:0];

    timeRemaining = nil;
    if([now compare:self.date1] == NSOrderedAscending){
        timeRemaining = [NSString stringWithFormat:@"%02d:%02d:%02d", [components hour], [components minute], [components second]];
        NSLog(@"works %@", timeRemaining);
    } else {
        timeRemaining = [NSString stringWithFormat:@"00:00:00"];
        [self.timer invalidate];
        self.timer = nil;
        if (self.alertView == NULL){
       self.alertView = [[UIAlertView alloc]initWithTitle:[testTask taskName] message:@"Time is up!" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
        [alertView performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:YES];       
        NSLog(@"ended");
        }
    }
   timerLabel.text = timeRemaining;
    [timerLabel setNeedsDisplay];
    [self.view setNeedsDisplay];
}
- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex{
    self.alertView = NULL;
}

所以基本上当应用程序在后台时计时器应该继续（它将根据计算的时间发送警报）。这意味着当您单击返回并重新点击单元格时，计时器应该会继续。它不这样做的原因是每次我点击一个单元格（或行）时，DetailViewController 都会被分配。我不知道如何解决这个问题，这样我就可以节省时间并根据需要开始/暂停。

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1 回答 1

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当您回击并以某种方式保存时，您需要跟踪计时器上的时间。您可以通过 NSUserDefaults 保存它，这将是最简单的，但由于您可以有多个计时器，所以做一个简单的 CoreData 应用程序可能会更干净。

逻辑（如果我正确理解您的问题）：

1. User pushes to DetailView and timer starts
2. User wants to pop back
  2.1 Save the date the timer started to the task record
3. User wants to go back to same task
  3.1 Load the NSDate of when the timer started from disk
  3.2 Calculate the offset from then until now
  3.3 Add that to the clock
  3.4 Start the timer with the offset added

希望有帮助。

于 2013-07-10T20:11:44.843 回答