As someone who loves JavaScript as much as I do, I never expected to be working in Xamarin. But that’s where I’ve been since I started my awesome new job! Xamarin brings some interesting challenges. You might think it’s just regular old C#, but since Xamarin uses MVVM architecture versus MVC architecture, I found a few things very tricky to manage. In this blog post, we’ll talk about how I managed navigation in a master detail app.

So in this app we used a master-detail app, which included a hamburger menu. The master property contained the hamburger menu, while the detail contained whichever partial view page was meant to be the current content. The code behind included a built-in Navigation property. You can use it like this:

await Navigation.PushAsync(new MyPage());


According to Xamarin docs, most or all of our app’s logic should be moved to the ViewModel. You can access the navigational properties via App.Current.MainPage.Navigation and push pages to the stack, as well as remove pages. However, I ran into a problem where the hamburger menu was disappearing when I would use App.Current.MainPage.Navigation. I realized I needed to find a way to actually update the Detail property itself. Unfortunately the Detail property doesn’t seem to be easily accessible. So I added a new constructor to the MainPage like this:

// MainPage.xaml.cs
// MainPage constructor
public MainPage(string page, params object[] args) {
Type myPage = Type.GetType(page);
}

// FlowerPage.xaml.cs
// call MainPage page and pass in page, and any parameters
string type = typeof(FlowerDetailPage).AssemblyQualifiedName;
List<string> params = new List<string>();



This works well enough, however it seems a little yucky to keep adding new MainPages to the navigation stack. It seems like it would be better to directly update the Detail property, but how can we access it?

We ended up creating a navigational client with a method like this:

// NavigationClientManager.cs
public static async Task SetDetail(Type page, param object[] args) {
Page detailPage = (Page)Activator.CreateInstance(page, args);
}

// FlowerPage.xaml.cs
// set the detail page
List<string> params = new List<string>();

This allows the ViewModel to simply call the SetDetail method, and avoid all of the casting of types in the nav client. It really cleans up the ViewModels and makes it very clear what is going on.