新手求助：Xamarin Forms跨平台实现特定Toggle Button是否需导入Material Design库？

Hey there! As someone who’s tinkered with Xamarin.Forms for a while, I can definitely help you out here.

First off: Yes, you absolutely can implement the toggle button effect you’re aiming for across both Android and iOS—and no, you don’t have to import the Material Design library to do it. Let me walk you through your options:

Option 1: Build it from scratch (no external libraries needed) #

This approach gives you full control over the button’s appearance, and relies on Xamarin.Forms’ custom renderers or built-in controls with styling tweaks:

Sub-option 1a: Custom Toggle Button + Custom Renderers #

1. Shared Project: Create a custom bindable control to hold the toggle state:

   public class CustomToggleButton : Button
   {
       public static readonly BindableProperty IsToggledProperty =
           BindableProperty.Create(nameof(IsToggled), typeof(bool), typeof(CustomToggleButton), false);
   
       public bool IsToggled
       {
           get => (bool)GetValue(IsToggledProperty);
           set => SetValue(IsToggledProperty, value);
       }
   }
   

2. Android Project: Write a custom renderer to use Android’s native ToggleButton (or style a regular Button to act as a toggle):

   [assembly: ExportRenderer(typeof(CustomToggleButton), typeof(CustomToggleButtonRenderer))]
   namespace YourAppNamespace.Droid.Renderers
   {
       public class CustomToggleButtonRenderer : ButtonRenderer
       {
           public CustomToggleButtonRenderer(Context context) : base(context) { }
   
           protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
           {
               base.OnElementChanged(e);
   
               if (Control != null && Element is CustomToggleButton toggleBtn)
               {
                   // Replace with your custom drawable selector for toggled/untoggled states
                   var nativeToggle = new Android.Widget.ToggleButton(Context);
                   nativeToggle.SetBackgroundResource(Resource.Drawable.toggle_state_selector);
                   
                   // Sync native state with your custom control
                   nativeToggle.CheckedChange += (s, args) => toggleBtn.IsToggled = args.IsChecked;
                   SetNativeControl(nativeToggle);
               }
           }
       }
   }
   

3. iOS Project: Similarly, create a renderer that uses a UIButton with state-specific styling (e.g., different background images for selected/unselected):

   [assembly: ExportRenderer(typeof(CustomToggleButton), typeof(CustomToggleButtonRenderer))]
   namespace YourAppNamespace.iOS.Renderers
   {
       public class CustomToggleButtonRenderer : ButtonRenderer
       {
           protected override void OnElementChanged(ElementChangedEventArgs<Button> e)
           {
               base.OnElementChanged(e);
   
               if (Control != null && Element is CustomToggleButton toggleBtn)
               {
                   Control.TouchUpInside += (s, args) =>
                   {
                       toggleBtn.IsToggled = !toggleBtn.IsToggled;
                       // Update button appearance based on IsToggled state
                       Control.SetBackgroundImage(toggleBtn.IsToggled ? UIImage.FromBundle("toggled_on") : UIImage.FromBundle("toggled_off"), UIControlState.Normal);
                   };
               }
           }
       }
   }
   

Sub-option 1b: Style the built-in Switch control #

If you don’t want to write full custom renderers, you can take Xamarin.Forms’ default Switch control and customize its appearance via platform-specific styles or renderers. For example, on Android you can override the switch track and thumb drawables; on iOS you can adjust the switch’s tint colors or replace its visuals entirely.

Option 2: Use Material Design (easier, but optional) #

If you want to save time and leverage pre-built Material Design components, enabling Xamarin.Forms’ Material Visual or using libraries like Xamarin.Forms.Material will let you use a Material-style toggle button with minimal code. This is great if you’re already adopting Material Design across your app, but it’s by no means a requirement.

Final Takeaway #

You’ve got full flexibility here. Whether you want to build a custom toggle from scratch (no external dependencies) or use Material Design to speed things up, both approaches work for Android and iOS.

内容的提问来源于stack exchange，提问作者George