UITableViewCell倒數UILabel未更新

Question

我試圖了解有關計時器的更多信息，所以我決定嘗試創建Todo列表類型的IOS應用。 在應用程序中，我希望用戶可以根據需要向每個任務/項目添加計時器。

到目前為止，用戶可以選擇一個時間（從選擇器中選擇），啟動和停止計時器而沒有任何問題。 我遇到的問題是UILabel將不會更新並顯示倒數計時器文本。 它唯一更新的時間是當我轉到一個子視圖（編輯任務），然后返回到主viewController（任務列表）時。

我可以更新單元格的唯一方法是使用[self.tableView reloadData]在父viewController中運行循環； 我很確定這就像用大錘殺死蒼蠅一樣。

任何見識都會很棒。 謝謝。

編輯 ：

@property (strong, nonatomic) IBOutlet UILabel *taskNameTextLabel; //Textfield for item
@property (strong, nonatomic) IBOutlet UILabel *taskSubtitleTextLabel; //Textfield to timer

我為tableview單元創建了一個子面板。 這是我在taskTableViewCell.m文件中用於計時器的代碼。

-(void) stopTimer {
    [self.timer invalidate];
    self.timer = nil;
}

- (void) startTimer
{
    [self stopTimer];
    NSLog(@"time : %f", _taskCountDownInterval);

    [self calculateTimer];
    _timer = [NSTimer timerWithTimeInterval:1.0
                                             target:self
                                           selector:@selector(countDownTimerHandler)
                                           userInfo:nil repeats:YES];
    [[NSRunLoop mainRunLoop] addTimer:_timer forMode:NSRunLoopCommonModes];
}

- (void)calculateTimer
{
    //calculate total seconds from the saved values the user selected using the picker.
    int hours = [self.startHours integerValue];
    int minutes = [self.startMinutes integerValue];
    int seconds = [self.startSeconds integerValue];
    NSLog(@"h: %i m: %i s: %i", hours,minutes,seconds);

    //convert to seconds and get total sum
    hours = hours *3600;
    minutes = minutes *60;
    int totalSeconds = hours + minutes + seconds;
    _taskCountDownInterval = totalSeconds;
}


- ( void) countDownTimerHandler
{
    int remainingTime = _taskCountDownInterval--;
    if (remainingTime <=0)
    {
        [_countDownTimer invalidate];
        _countDownTimer = nil;
        remainingTime = 0;
        NSLog(@"Timer finished!");
    }
    //convert for text display.
   int hours = remainingTime / 3600;
   int scratch = remainingTime % 3600;
   int minutes = scratch / 60;
   int seconds = scratch % 60;

    NSString *timeValue = [NSString stringWithFormat:@"%i:%i:%i",hours,minutes,seconds];
    self.subtitle = timeValue; //save the converted string.

    NSLog(@"label should be  %@",timeValue);
    NSLog(@"label is  %@",self.taskSubtitleTextLabel.text);
    //[[self taskSubtitleTextLabel] setText:_subtitle];
    _taskSubtitleTextLabel.text = _subtitle;
}

日志輸出為：

2014-06-18 11:52:22.614 mytools2[1438:60b] turn timer ON
2014-06-18 11:52:22.614 mytools2[1438:60b] total time in seconds : 21966.000000
2014-06-18 11:52:22.615 mytools2[1438:60b] h: 6 m: 6 s: 6
2014-06-18 11:52:22.615 mytools2[1438:60b] taskCountDownInterval 21966.000000
2014-06-18 11:52:23.616 mytools2[1438:60b] label should be  6:6:6
2014-06-18 11:52:23.617 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:24.616 mytools2[1438:60b] label should be  6:6:5
2014-06-18 11:52:24.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:25.616 mytools2[1438:60b] label should be  6:6:4
2014-06-18 11:52:25.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:26.616 mytools2[1438:60b] label should be  6:6:3
2014-06-18 11:52:26.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:27.616 mytools2[1438:60b] label should be  6:6:2
2014-06-18 11:52:27.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:28.616 mytools2[1438:60b] label should be  6:6:1
2014-06-18 11:52:28.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:29.616 mytools2[1438:60b] label should be  6:6:0
2014-06-18 11:52:29.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:30.615 mytools2[1438:60b] label should be  6:5:59
2014-06-18 11:52:30.616 mytools2[1438:60b] label is  (null)
2014-06-18 11:52:30.773 mytools2[1438:60b] turn timer OFF

Answer 1

您可以使用reloadRowsAtIndexPaths:withRowAnimation:僅更新需要更新的單元格（包含標簽的單元格），而不是更新整個表：

[self.tableView reloadRowsAtIndexPaths:@[yourIndexPath] withRowAnimation: UITableViewRowAnimationNone]