How to access ViewWillAppear/ViewDidDisappear in ViewRenderer<HybridWebView, WkWebViewRenderer>? - xamarin.forms

Question

I'm trying to port an Android existing custom ViewRenderer to iOS.
I'm using version 4.8 of Xamarin.Forms.
Specifically, I need to match Android's OnAttachedToWindow & OnDetachedFromWindow.
The Android Code is like the following:
public partial class HybridWebViewRenderer : ViewRenderer<HybridWebView, Android.Webkit.WebView>
{
protected override void OnAttachedToWindow()
{
base.OnAttachedToWindow();
...
}
protected override void OnDetachedFromWindow()
{
base.OnDetachedFromWindow();
...
}
}
According to this link, I would need to override ViewWillAppear which is the iOS equivalent to OnAttachedToWindow.
The custom Renderer for iOS is the following:
public partial class HybridWebViewRenderer : ViewRenderer<HybridWebView, WkWebViewRenderer>, IWKScriptMessageHandler
{
}
But the overrides are not available.
How can I do that?

Answer 1

ViewWillAppear and ViewWillDisappear are the life cycle method of UIViewController.So you could create the custom renderer of ContentPage
in the ContentPage that contains the WebView
using Foundation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
using App1;
using App1.iOS;
[assembly:ExportRenderer(typeof(MainPage),typeof(MyPageRenderer))]
namespace App1.iOS
{
public class MyPageRenderer:PageRenderer
{
public override void ViewWillAppear(bool animated)
{
base.ViewWillAppear(animated);
MessagingCenter.Send<Object,UIViewController>(this,"ViewWillAppear",this); // send message when the method been called .
}
public override void ViewWillDisappear(bool animated)
{
base.ViewWillDisappear(animated);
MessagingCenter.Send<Object, UIViewController>(this, "ViewWillDisappear", this);
}
}
}
in WebViewRenderer
Subscribe the message in the constructor .
MessagingCenter.Subscribe<Object, UIViewController > (this, "ViewWillDisappear",(arg,controller)=> {
// controller is the current UIViewController
});