保存设置之后，你应该改变的细节的已有的的MasterDetailPage实例。

After saving the settings you should change the detail of an exisiting MasterDetailPage instance.

我觉得这样做最简单和最清晰的方法是使用的 MessagingCenter ：

I think the simplest and clearest way to do this is using MessagingCenter:

在设置页面：

MessagingCenter.Send(new OpenMyPageMessage(), OpenMyPageMessage.Key);

您主从页面：

protected override void OnAppearing()
{
    MessagingCenter.Subscribe<OpenMyPageMessage>(this, OpenMyPageMessage.Key, (sender) =>
        {
            Detail = new YourAnotherPage();
        });
}

protected override void OnDisappearing()
{
    MessagingCenter.Unsubscribe<OpenMyPageMessage>(this, OpenMyPageMessage.Key);
}

和 OpenMyPageMes​​sage 是只是一个简单的类：

And OpenMyPageMessage is just a simple class:

public class OpenMyPageMessage
{
    public static string Key = "OpenMyPageMessage";
}

结果：
的