Custom Alert Dialog if internet connection is not available

Hi Try this code

 

Android.Net.ConnectivityManager connectivityManager = (Android.Net.ConnectivityManager)GetSystemService(ConnectivityService);
Android.Net.NetworkInfo activeConnection = connectivityManager.ActiveNetworkInfo;
bool isOnline = (activeConnection != null) && activeConnection.IsConnected;
if (isOnline == false)
{
var errorMessage = "Network Connection Failed";
Android.App.AlertDialog.Builder builder = new Android.App.AlertDialog.Builder(this);
builder.SetTitle("Result");
builder.SetMessage(errorMessage);
builder.SetCancelable(false);
builder.SetNegativeButton("OK", (EventHandler)null);
builder.Show();

} 

You can implement in javascript :

 

https://www.kirupa.com/html5/check_if_internet_connection_exists_in_javascript.htm

 

or in C#

 

http://stackoverflow.com/questions/20309158/c-sharp-checking-internet-connection

 

Regarding custom alert you have to implement manually.

 

https://www.w3schools.com/howto/howto_js_alert.asp

 

http://bootboxjs.com/examples.html