[用户单击不滚动时如何更改所选项目

Question

我在选择器更新模式上遇到问题搜索后找到此行“ iOSSpecific:Picker.UpdateMode="WhenFinished"”添加到我的自定义选择器后，所选项目未更改

protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
{
    base.OnElementChanged(e);
    var extendedPicker = e.NewElement as CustomPicker;
    if (extendedPicker == null) return;

    var toolbar = new UIToolbar(new CGRect(0.0f, 0.0f, Control.Frame.Size.Width, 44.0f));

    toolbar.Items = new[]
    {
    new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
    new UIBarButtonItem("Yes",
        UIBarButtonItemStyle.Done,
        delegate {
            Control.ResignFirstResponder();
        })
    };

    if (this.Control != null)
    {
        Control.InputAccessoryView = toolbar;
    }
}

Answer 1

选择值。

尝试使用渲染器中的跟踪代码：

public class CustomPickerRenderer : PickerRenderer, IUIPickerViewDelegate, IUIPickerViewDataSource
{
    string SelectedValue;

    protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
    {
        base.OnElementChanged(e);

        SelectedValue = Element.Items[0];

        UIPickerView pickerView = (UIPickerView)Control.InputView;
        pickerView.WeakDelegate = this;
        pickerView.DataSource = this;
        pickerView.Delegate = new deleagteClass();

        var toolbar = new UIToolbar(new CGRect(0.0f, 0.0f, Control.Frame.Size.Width, 44.0f));

        toolbar.Items = new[]
        {
            new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
            new UIBarButtonItem("Yes",
                UIBarButtonItemStyle.Done,
                delegate {
                    Control.ResignFirstResponder();
                    Control.Text = SelectedValue;
                })
        };

        if (this.Control != null)
        {
            Control.InputAccessoryView = toolbar;
        }
    }

    public nint GetComponentCount(UIPickerView pickerView)
    {
        return 1;
    }

    public nint GetRowsInComponent(UIPickerView pickerView, nint component)
    {
        return Element.Items.Count;
    }

    [Export("pickerView:viewForRow:forComponent:reusingView:")]
    public UIView GetView(UIPickerView pickerView, nint row, nint component, UIView view)
    {

        UILabel label = new UILabel
        {
            TextColor = UIColor.Black,
            Text = Element.Items[(int)row].ToString(),
            TextAlignment = UITextAlignment.Center,
        };
        var picker = this.Element;
        return label;
    }

    [Export("pickerView:didSelectRow:inComponent:")]
    public void Selected(UIPickerView pickerView, nint row, nint component)
    {
        SelectedValue = Element.Items[(int)row];
    }
}

效果：