由於Digitalsa1nt表示,Picker
沒有PlaceholderText
屬性。但是,您可以通過custom renderer添加此屬性。
CustomPicker.cs
public class CustomPicker : Picker
{
public static readonly BindableProperty PlaceHolderProperty = BindableProperty.Create(
propertyName: "PlaceHolder",
eturnType: typeof(string),
declaringType: typeof(CustomPicker),
defaultValue: default(string));
public string PlaceHolder
{
get { return (string)GetValue(PlaceHolderProperty); }
set { SetValue(PlaceHolderProperty, value); }
}
}
實現CustomPickerRenderer
在UWP客戶端項目。
CustomPickerRenderer.cs
[assembly: ExportRenderer(typeof(CustomPicker), typeof(CustomPickerRenderer))]
namespace XamarinPickerDefaultValueTest.UWP
{
public class CustomPickerRenderer : PickerRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
{
base.OnElementChanged(e);
var element = Element as CustomPicker;
if (Control != null)
{
Control.PlaceholderText = element.PlaceHolder;
}
}
}
}
使用
<local:CustomPicker PlaceHolder="Picker something" x:Name="picker"/>
拾荒者沒有任何形式的 '佔位' 的功能,你就必須有一個您的源綁定中的額外項目可以與您中的其他項目區分開來r源作爲默認選定索引。 – Digitalsa1nt