xamarin.forms - iOS 14 DatePicker 渲染器

Question

我在弄清楚如何正确更新 iOS 上的 DatePicker 现有的自定义渲染器以显示具有不同首选样式的 DatePicker 时遇到了一些困难，如本文中所述(尽管它是针对 swift)https://medium.com/better-programming/introducing-swifts-new-modern-date-picker-37bb5e0a106

我的渲染器如下:

public class BorderlessDatePickerRenderer : DatePickerRenderer
    {
        
        public override void LayoutSubviews()
        {
            base.LayoutSubviews();
            
            
            var element = Element as BorderlessDatePicker;
            Control.BorderStyle = UITextBorderStyle.None;
            if (element.Date.Year == 1900) {
                    Control.Text = "";
            }
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            var element = Element as BorderlessDatePicker;

            if (Control != null && element.Date.Year == 1900) {
                    Control.Text = "";
            }
        }

BorderlessDatePicker 本身只是一个扩展 DatePicker Xamarin.Forms 控件的空类。我的问题的根源在于，我不确定如何在 Control 对象上正确设置 PreferredDatePickerStyle ，因为 Control 是一个 UITextField 而不是 UIDatePicker。本质上，我想做的不是使用似乎是 iOS 14 默认的 compact 样式显示日期选择器，而是希望将其显示为 wheels code> 而不是做类似的事情:

PreferredDatePickerStyle = UIDatePickerStyle.Wheels;

Answer 1

经过更多研究并浏览 xamarin github，我发现了这个解决方案:

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

        if(e.NewElement != null && this.Control != null)
        {
            try
            {
                if (UIDevice.CurrentDevice.CheckSystemVersion(14, 0))
                {
                    UIDatePicker picker = (UIDatePicker)Control.InputView;
                    picker.PreferredDatePickerStyle = UIDatePickerStyle.Wheels;
                }

            } catch (Exception ex)
            {
                Log.Error(ex, "Failed to set PreferredDatePickerStyle to be UIDatePickerStyle.Wheels for iOS 14.0+");
            }
        }
    }