OnLoadAsync:

This method is invoked during page initialization. The developer can override it, and it has the following parameter: PageLoadEventArgs: this object has a CancellationToken property that is used to propagate a notification indicating that operations should be canceled.

OnActivatedAsync:

This method is invoked when the page is reactivated (when the tab is selected). The developer can override it, and it has the following parameter: PageActivatedEventArgs: this object has a CancellationToken property that is used to propagate a notification indicating that operations should be canceled.

OnClosingAsync:

This method is invoked when the interface requests closing the current page. The developer can override it, and it has the PageClosingEventArgs parameter. This object has two properties: Cancel: set to true if you want to cancel closing the page. ConfirmationMessage: display a confirmation dialog if this message is not empty.

private bool _confirmAsked;

protected override Task OnClosingAsync(PageClosingEventArgs e)
{
    _confirmAsked = (new Random()).NextDouble() >= 0.5;
    if (_confirmAsked)
    {
        e.ConfirmationMessage = "Are you sure?";
        //            OR
        //            e.Cancel = true;
        //            ShowConfirm("Message", ForceCloseAsync);
    }
    return Task.CompletedTask;
}

OnCloseAsync:

This method is invoked when the current page must be closed. The developer can override it, and it has the EventArgs parameter.

private bool _confirmAsked;

protected override async Task OnCloseAsync(EventArgs e)
{
    await base.OnCloseAsync(e);
    ShowInformation($"CLOSE ! {_confirmAsked}");
}