在TabbarRenderer Xamarin.iOS中取消导航

Question

I have a custom tabbar renderer for iOS in a Xamarin.Forms app. In certain cases, I need to stop the ItemSelected event. Essentially, if the user taps the item on the tabbar, I need to perform a custom action and NOT navigate.

It seems that the ItemSelectedevent is too late to do this. I know that there is a ShouldShowViewController method on the UITabbarController , but this has been abstracted away by the TabbarRenderer .

How can I achieve this?

Answer 1

Solution:

There is a method SelectViewController .It return a bool value .If return True ,it will navigate a new page when you select the item ,and won't if return false.You can refer the following code.(For example you don't want to navigate when you click the second child page on tabbed page )

in Custom Renderer

private xxx page;//xxx is your tabbedPage in forms

protected override void OnElementChanged(VisualElementChangedEventArgs e)
{
  base.OnElementChanged(e);

  if(e.NewElement!=null)
  {
    page = (xxx)e.NewElement;
  }

  else
  {
    page = (xxx)e.OldElement;
  }

  if (this.Element != null)
  {
     UITabBarController tabbar = (UITabBarController)this.ViewController;

     tabbar.ShouldSelectViewController += SelectViewController;

  }

}


public  bool SelectViewController(UITabBarController tabBarController, UIViewController viewController)
{
  if(viewController==this.ViewControllers[1])
  {
    //do something you want 

    return false;
  }

  else
  {
    return true;
  }

}