如何以编程方式让 UITableView 滚动到特定部分

Question

在我的日历应用程序中，我希望我的 UITableView 根据点击的日期滚动到特定部分。 当前的实现如下：

- (void)calendarDidDateSelected:(JTCalendar *)calendar date:(NSDate *)date
{
    // Format NSDate so it can be compared to date selected
    static NSDateFormatter *dateFormatter = nil;
    if(!dateFormatter){
        dateFormatter = [NSDateFormatter new];
        dateFormatter.dateFormat = @"yyyy-MM-dd"; // Read the documentation for dateFormat
    }

    // Set formatted dates
    NSDate *juneSixteenth = [dateFormatter dateFromString:@"2015-06-16"];
    NSDate *juneSeventeenth = [dateFormatter dateFromString:@"2015-06-17"];

    // Set date selected, so agendaTable knows which event to show
    if([juneSixteenth compare:date] == NSOrderedSame){
        NSLog(@"You picked June 16th");
        self.datePicked = [NSNumber numberWithInt:16];
    }
    else if([juneSeventeenth compare:date] == NSOrderedSame){
        NSLog(@"You picked June 17th");
        self.datePicked = [NSNumber numberWithInt:17];
    }
    else {
        _datePicked = nil;
        NSLog(@"Date: %@", date);
    }
    [self.agendaTable reloadData];
}

我发现了一个类似的问题，说要这样做：

       if([juneSixteenth compare:date] == NSOrderedSame){
            NSLog(@"You picked June 16th");
            self.datePicked = [NSNumber numberWithInt:16];

            //"row" below is row selected in the picker view
            NSIndexPath *ip = [NSIndexPath indexPathForRow:0 inSection:row];

            [self.agendaTable scrollToRowAtIndexPath:ip
                          atScrollPosition:UITableViewScrollPositionNone
                                  animated:YES];
        }

这给出了一个错误，指出row是一个未声明的标识符，我希望它使用节索引而不是行。 我将如何实现这一点？

Answer 1

尝试这个

[NSIndexPath indexPathForRow:NSNotFound inSection:section]

Answer 2

斯威夫特 3.0

DispatchQueue.main.async {
   let indexPath = IndexPath(item: 'item', section: 'section')
   self.tableView.scrollToRow(at: indexPath, at: .top, animated: true)
}

Answer 3

@black-sheep 答案的 Swift 版本：

let sectionIndexPath = IndexPath(row: NSNotFound, section: section)

Answer 4

当您的部分没有单元格时，例如它只有页眉或页脚，您可以使用以下选项之一：

let sectionRect = yourTable.rect(forSection: sectionNumber)
yourTable.setContentOffset(CGPoint(x: sectionRect.origin.x, y: sectionRect.origin.y), animated: true)

或者

let sectionRect = yourTable.rect(forSection: sectionNumber)
yourTable.scrollRectToVisible(sectionRect, animated: false)

Answer 5

行必须是 int 值，该变量定义在 .h 中，并在 .m 类中的任何地方使用此变量，您要在特定位置滚动。

您可以在特定部分滚动 UITableView，也可以使用以下代码滚动到部分的特定索引单元格：

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[MytblView scrollToRowAtIndexPath:indexPath 
                     atScrollPosition:UITableViewScrollPositionTop 
                             animated:YES];

Answer 6

您必须找到/计算要滚动的section和row

NSInteger row = ??;//you have to find/calculate which row you want to show
NSInteger section = ??;//you have to find/calculate which row of the sections you want to show
NSIndexPath *ip = [NSIndexPath indexPathForRow:row inSection:section];

[self.agendaTable scrollToRowAtIndexPath:ip
                        atScrollPosition:UITableViewScrollPositionNone
                                animated:YES];