如何在Xamarin.Forms左側設置ToolbarItem？

Question

我想在導航欄的左側設置一個ToolbarItem，但我不知道如何設置它。 Xamarin.Forms的默認ToolbarItem在右側

Answer 1

在iOS中我使用自定義渲染器，我不認爲它有任何方法。在Android中，我並不打擾，因爲人們習慣於右側的項目。下面的渲染器檢查是否有多個ToolBarItems，如果是，則將其移動到左側。

[assembly: ExportRenderer(typeof(ContentPage), typeof(LeftNavigationItemRenderer))] 
namespace MyApp.iOS 
{ 
    public class LeftNavigationItemRenderer : PageRenderer 
    { 
     public override void ViewWillAppear(bool animated) 
     { 
      base.ViewWillAppear(animated); 

      if (NavigationController == null) 
       return; 

      var navigationItem = NavigationController.TopViewController.NavigationItem; 
      var leftNativeButtons = (navigationItem.LeftBarButtonItems ?? new UIBarButtonItem[] { }).ToList(); 
      var rightNativeButtons = (navigationItem.RightBarButtonItems ?? new UIBarButtonItem[] { }).ToList(); 

      if (rightNativeButtons.Count > 1) 
      { 
       var nativeItem = rightNativeButtons.Last(); 
       rightNativeButtons.Remove(nativeItem); 
       leftNativeButtons.Add(nativeItem); 
      } 

      navigationItem.RightBarButtonItems = rightNativeButtons.ToArray(); 
      navigationItem.LeftBarButtonItems = leftNativeButtons.ToArray(); 
     } 
    } 
}