Question

我想设置在用户在我的tableview中点击的任何单元格内的标签内运行的经过时间或持续时间计时器。 dataSource和delegate是托管ViewController。

我将一个标签拖到tableview中的原型单元格中，然后使用以下代码来驱动标签中的文本：

首先，tableview方法：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    [self configureCell:cell atIndexPath:indexPath];

    cell.textLabel.textColor = [UIColor redColor];
    NSAttributedString *attString;
    attString = cell.textLabel.attributedText;
    return cell;
}



- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

    //Tasks
    // 1) Create new TimedActivity object timestamped now, named and categorized
    // 2) Start updating label giving duration of selected activity.
    // 3) Each cell must have a label

    TimedActivity *previousTimedActivity = [TimedActivity MR_findFirstOrderedByAttribute:@"startTime" ascending:NO];

    NSManagedObjectContext *localContext = [NSManagedObjectContext MR_contextForCurrentThread];
    WMDGActivity *thisActivity = [actFRC objectAtIndexPath:indexPath];

    //Create fresh TimedActivity object
    currentTimedActivity = [TimedActivity MR_createInContext:localContext];

    //Name the attributes
    currentTimedActivity.name = thisActivity.name;
    currentTimedActivity.category = thisActivity.category;
    currentTimedActivity.startTime = [NSDate date];
    previousTimedActivity.stopTime = currentTimedActivity.startTime;

    //previousActivityDuration

    NSTimeInterval previousActivityDuration = [previousTimedActivity.stopTime timeIntervalSinceDate:previousTimedActivity.startTime];
    previousTimedActivity.duration = @(previousActivityDuration);

    [localContext MR_saveToPersistentStoreAndWait];

    // I put this line here to delay updates so the start time is not the same as "Now"
    [self performSelector:@selector(updateTime) withObject:nil afterDelay:0.5f];

    // Timer regulates the readout updates in the label
    [NSTimer scheduledTimerWithTimeInterval:1
                                     target:self
                                   selector:@selector(updateTime)
                                   userInfo:nil
                                    repeats:YES];

    [self updateTime];
    [self refreshData];


}

标签文字的设置如下：

-(void)updateTime
{


    //Which calendar
    NSCalendar *calendar = [NSCalendar currentCalendar];

    //Gets the componentized interval from the most recent time an activity was tapped until now
    NSDateComponents *components= [calendar components:NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit fromDate:currentTimedActivity.startTime toDate:[NSDate date] options:0];

    NSInteger hours = [components hour];
    NSInteger minutes = [components minute];
    NSInteger seconds =[components second];

    if(!seconds)
    {
        [timer invalidate];

    }
    //Converts the components to a string and displays it in the duration label
    self.durationLabel.text = [NSString stringWithFormat:@"%02i:%02i:%02i",hours,minutes,seconds];

    NSLog(@"The label should be reading %02i:%02i:%02i",hours,minutes,seconds);

    NSLog(@"Label is actually reading %@",self.durationLabel.text);
}

结果是一个空白标签，虽然时间在NSLogs中是正确的：

MR_saveWithOptions:completion:]_block_invoke21(0x8db66c0) → Finished saving: <NSManagedObjectContext (0x8db66c0): *** BACKGROUND SAVING (ROOT) ***> on *** MAIN THREAD ***
2014-03-11 12:21:16.075 WMDGx[51203:a0b] The label should be reading 00:00:00
2014-03-11 12:21:16.076 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:16.575 WMDGx[51203:a0b] The label should be reading 00:00:00
2014-03-11 12:21:16.575 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:17.075 WMDGx[51203:a0b] The label should be reading 00:00:01
2014-03-11 12:21:17.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:18.075 WMDGx[51203:a0b] The label should be reading 00:00:02
2014-03-11 12:21:18.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:19.075 WMDGx[51203:a0b] The label should be reading 00:00:03
2014-03-11 12:21:19.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:20.074 WMDGx[51203:a0b] The label should be reading 00:00:04
2014-03-11 12:21:20.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:21.074 WMDGx[51203:a0b] The label should be reading 00:00:05
2014-03-11 12:21:21.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:22.074 WMDGx[51203:a0b] The label should be reading 00:00:06
2014-03-11 12:21:22.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:23.074 WMDGx[51203:a0b] The label should be reading 00:00:07
2014-03-11 12:21:23.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:24.074 WMDGx[51203:a0b] The label should be reading 00:00:08
2014-03-11 12:21:24.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:25.074 WMDGx[51203:a0b] The label should be reading 00:00:09
2014-03-11 12:21:25.075 WMDGx[51203:a0b] Label is actually reading (null)
2014-03-11 12:21:26.074 WMDGx[51203:a0b] The label should be reading 00:00:10
2014-03-11 12:21:26.075 WMDGx[51203:a0b] Label is actually reading (null)

我显然忽视了某些事情，如果历史是一个指南，那将是显而易见的事情。但是，我找不到它。

有人可以给我指路吗？

谢谢！

如何在UITableViewCell内的标签中更新运行计时器

0 个答案: