iOS TableView重新加载并滚动顶部 [英] iOS TableView reload and scroll top

问题描述

第二天我无法解决表中的问题。

the second day I can not solve the problem with the table.

我们有一个segmentedControl，当更改时，会更改表格。
假设控件的段中有3个元素，相应地，3个数组（重要的是，它们的大小不同）
我需要在更改segmentedControl时向上滚动表。

We have a segmentedControl which, when changed, changes the table. Suppose that there are 3 elements in the segment of the control and, correspondingly, 3 arrays (which is important, they are of different sizes) I need to scroll table up when segmentedControl is changed.

似乎一切都很简单：contentOffset = .zero和reloadData（）

And it seems like everything is simple: contentOffset = .zero and reloadData ()

但是。这不起作用，我不知道为什么桌子不向上滚动。

But. This does not work, I do not know why the table not scroll up.

唯一有效的方法：

UIView.animate (withDuration: 0.1, animations: {
            self.tableView.contentOffset = .zero
        }) {(_) in
            self.tableView.reloadData ()
}

但现在表格还有另一个问题up，可能会出现bug，因为segmentedControl已经改变了，而另一个数组中的数据可能没有，我们还没有完成reloadData（）

But now there is another problem when the table goes up, a bug may occur, because the segmentedControl has changed, and the data in the other array may not be, we have not yet done reloadData ()

也许我可以不明白明显的事情）祝贺即将到来的假期！

Maybe I can not understand the obvious things)) Congrats on the upcoming holidays!

推荐答案

UItableView 方法 scrollToRow（at：at：animated :) 滚动浏览表视图直到由索引路径标识的行处于特定的lo屏幕上显示阳离子。

UItableView method scrollToRow(at:at:animated:) Scrolls through the table view until a row identified by index path is at a particular location on the screen.

使用

tableView.scroll(to: .top, animated: true)

你可以使用我的扩展

extension UITableView {

    public func reloadData(_ completion: @escaping ()->()) {
        UIView.animate(withDuration: 0, animations: {
            self.reloadData()
        }, completion:{ _ in
            completion()
        })
    }

    func scroll(to: scrollsTo, animated: Bool) {
        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(300)) {
            let numberOfSections = self.numberOfSections
            let numberOfRows = self.numberOfRows(inSection: numberOfSections-1)
            switch to{
            case .top:
                if numberOfRows > 0 {
                     let indexPath = IndexPath(row: 0, section: 0)
                     self.scrollToRow(at: indexPath, at: .top, animated: animated)
                }
                break
            case .bottom:
                if numberOfRows > 0 {
                    let indexPath = IndexPath(row: numberOfRows-1, section: (numberOfSections-1))
                    self.scrollToRow(at: indexPath, at: .bottom, animated: animated)
                }
                break
            }
        }
    }

    enum scrollsTo {
        case top,bottom
    }
}

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