c# - 现在我不再需要显式订阅 property-changed-event，我可以简化这个 iOS 渲染器吗

Question

我正在使用这个自定义渲染器:

public class ExtViewCellRenderer : ViewCellRenderer
{
    UITableViewCell _nativeCell;

    public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)
    {
        _nativeCell = base.GetCell(item, reusableCell, tv);
        var formsCell = item as ExtViewCell;

        if (formsCell != null)
        {
            formsCell.PropertyChanged -= OnPropertyChanged;
            formsCell.PropertyChanged += OnPropertyChanged;
        }
        SetTap(formsCell);

        return _nativeCell;
    }

    void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        var formsCell = sender as ExtViewCell;
        if (formsCell == null)
            return;

        if (e.PropertyName == ExtViewCell.NoTapProperty.PropertyName)
        {
            SetTap(formsCell);
        }
    }

    private void SetTap(ExtViewCell formsCell)
    {
        if (formsCell.NoTap)
            _nativeCell.SelectionStyle = UITableViewCellSelectionStyle.None;
        else
            _nativeCell.SelectionStyle = UITableViewCellSelectionStyle.Default;
    }

}

我读到，使用 TextCellRenderer 不再需要显式订阅 property-changed-event，因为有一个可重写的基本方法 HandlePropertyChanged 可以重复使用在这种情况下。

有人可以告诉我 ViewCellRenderer 是否也是这种情况吗？如果是这样，我该如何修改此代码以利用它？

我也在另一个渲染器中看到这样的代码:

public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)
{
    var textCell = (TextCell)item;
    var fullName = item.GetType().FullName;
    cell = tv.DequeueReusableCell(fullName) as CellTableViewCell;

    //...

但这里没有。是否有必要这样做 Cell = tv.DequeueReusableCell ？

Answer 1

I read that with a TextCellRenderer it's no longer necessary to explicitly subscribe to property-changed-event as there is a base overridable method HandlePropertyChanged that can be re-used in this context.

是的，根据其源代码，这是正确的

protected virtual void HandlePropertyChanged(object sender, PropertyChangedEventArgs args) {
    //...
}

TextCellRenderer Source

Can someone tell me if this is the case also for the ViewCellRenderer and if so then how could I modify this code to make use of this?

不，根据源代码，ViewCellRenderer 也并非如此 ViewCellRenderer未公开其 ViewCellPropertyChanged 因为它是 private

void ViewCellPropertyChanged(object sender, PropertyChangedEventArgs e) {
    //...
}

ViewCellRenderer Source

您始终可以自己修改它并创建拉取请求以添加该功能。