iOS - UIDatePicker 更改显示日期动态

Question

我正在使用 DateCell example 中的代码我想将开始日期更改为我选择的日期(我从某处加载)。所以我正在更改 dataArray(包含 kTitleKey 和 kDateKey 的字典)和 dateCell 中的日期值，没关系。显示了我的日期，但是当我单击该单元格时，会显示 DatePicker ，并且其中有来自 StoryBoard 的默认日期。我猜问题出在 updateDatePicker 方法中:

- (void)updateDatePicker
{
    if (self.datePickerIndexPath != nil)
    {
        UITableViewCell *associatedDatePickerCell = [datePickersTableView cellForRowAtIndexPath:self.datePickerIndexPath];
        /*
        if (associatedDatePickerCell == nil) {
            associatedDatePickerCell = [datePickersTableView dequeueReusableCellWithIdentifier:kDatePickerID];
        }*/
        UIDatePicker *targetedDatePicker = (UIDatePicker *)[associatedDatePickerCell viewWithTag:kDatePickerTag];
        if (targetedDatePicker != nil)
        {
            // we found a UIDatePicker in this cell, so update it's date value
            //
            NSDictionary *itemData = self.dataArray[self.datePickerIndexPath.row - 1];
            [targetedDatePicker setDate:[itemData valueForKey:kDateKey] animated:NO];
        }
    }
}

由于某种原因，关联日期选择器单元始终为零。我尝试更改它(在注释中使用代码)，但它没有帮助(当时 AssociatedDatepickerCell 不是零，但日期仍然没有改变)。我在 itemData 中有正确的日期。

编辑:添加了cellForRowAtIndexPath的代码

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = nil;

    NSString *cellID;

    if ([self indexPathHasPicker:indexPath])
    {
        // the indexPath is the one containing the inline date picker
        cellID = kDatePickerID;     // the current/opened date picker cell
    }
    else
    {
        // the indexPath is one that contains the date information
        cellID = kDateCellID;       // the start/end date cells
    }
    //if ([self indexPathHasDate:indexPath])
    cell = [tableView dequeueReusableCellWithIdentifier:cellID];

    // if we have a date picker open whose cell is above the cell we want to update,
    // then we have one more cell than the model allows
    //
    NSInteger modelRow = indexPath.row;
    if (self.datePickerIndexPath != nil && self.datePickerIndexPath.row < indexPath.row)
    {
        modelRow--;
    }

    // proceed to configure our cell
    if ([cellID isEqualToString:kDateCellID])
    {
        NSDictionary *itemData = self.dataArray[modelRow];

        // we have either start or end date cells, populate their date field
        //
        cell.textLabel.text = [itemData valueForKey:kTitleKey];
        UILabel *custLabel = (UILabel*)[cell viewWithTag:2];
        custLabel.text = [self.dateFormatter stringFromDate:[itemData valueForKey:kDateKey]];
        UIView *dateView = (UIView*)[cell viewWithTag:3];
        [dateView.layer setBorderWidth:1];
        [dateView.layer setBorderColor:[[UIColor whiteColor] CGColor]];
        cell.detailTextLabel.text = [self.dateFormatter stringFromDate:[itemData valueForKey:kDateKey]];
    }

    [cell setBackgroundColor:[UIColor clearColor]];

    return cell;
}

Answer 1

谁在调用您的 updateDatePicker 方法？

问题在于，在其实现中，您尝试使用 cellForRowAtIndexPath: 获取单元格，这可能会或可能不会返回单元格，具体取决于时间、滚动位置等:

Return Value

An object representing a cell of the table or nil if the cell is not visible or indexPath is out of range.

您应该在 tableViewDataSource 中返回相应的单元格时更新选择器，该单元格位于您的 tableView:cellForRowAtIndexPath: 中，它只会被 TableView 延迟调用需要时。