将JSON反序列化为类失败，并显示“加载类型时发生故障”

Question

I have a REST API, with an endpoint that returns JSON. I call this API from a Xamarin app (iOS simulator), and I try to run the following call:

IEnumerable<Project> projects = null;

HttpResponseMessage response = await _client.GetAsync(url);

if (response.IsSuccessStatusCode)
{
    var jsonStr = await response.Content.ReadAsStringAsync();
    projects = JsonConvert.DeserializeObject<IEnumerable<Project>>(jsonStr);
}

In debugging, I can see that my jsonStr is perfectly valid, and if I use a service such as http://json2csharp.com/ , my classes are perfect.

However, what happens on the DeserializeObject object, is I get the error:

Failure has occurred while loading a type

I have 3 projects:

• App.ApiWrapper (portable class library)
• App
• App.iOS

All 3 have version 10.0.3 added under "Packages". Screenshot:

However, I keep getting this error (targeting iPhone 7 iOS 10.3.1):

Please help! I'm at the "throwing the computer out of the window" state :D

EDITS:

AppDelete of iOS app:

using System;
using System.Collections.Generic;
using System.Linq;

using Foundation;
using UIKit;

namespace EesyApp.iOS
{
    [Register("AppDelegate")]
    public partial class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
    {
        public override bool FinishedLaunching(UIApplication app, NSDictionary options)
        {
            global::Xamarin.Forms.Forms.Init();

            LoadApplication(new App());

            return base.FinishedLaunching(app, options);
        }
    }
}

Project.cs class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Asano.Wrapper.Api.Models
{
    public class Project
    {
        public Customer Customer { get; set; }
        public Signee Signee { get; set; }
        public int Id { get; set; }
        public int CustomerId { get; set; }
        public int SigneeId { get; set; }
        public int ProjectState { get; set; }
        public string DateCreated { get; set; }
        public object DateUpdated { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public int Source { get; set; }
    }

    public class Customer
    {
        public object Country { get; set; }
        public int Id { get; set; }
        public string Name { get; set; }
        public string VatNumber { get; set; }
        public string Address { get; set; }
        public string Zipcode { get; set; }
        public string City { get; set; }
        public object Region { get; set; }
        public object OfficePhone { get; set; }
        public object OfficeEmail { get; set; }
        public object CountryId { get; set; }
        public string DateCreated { get; set; }
        public object DateUpdated { get; set; }
        public object Email { get; set; }
    }

    public class Signee
    {
        public int Id { get; set; }
        public string DateCreated { get; set; }
        public object DateUpdated { get; set; }
        public object FirstName { get; set; }
        public object LastName { get; set; }
        public object CompanyName { get; set; }
        public object VatNumber { get; set; }
        public string Email { get; set; }
        public object PhoneNumber { get; set; }
        public int SigneeType { get; set; }
        public object Address { get; set; }
        public object Zipcode { get; set; }
        public object City { get; set; }
        public object Region { get; set; }
    }


}

StackTrace:

The Offers file calling LeadService:

The method that actually calls the API is callde GetBySpecification and is inside my LeadService.

  public partial class Offers : ContentPage
    {
        public Offers()
        {
            InitializeComponent();


        }

        protected async override void OnAppearing()
        {
            base.OnAppearing();


            LeadService leadService = new LeadService();
            var items = await leadService.GetBySpecification(new Asano.Wrapper.Api.Models.Specifications.ProjectSpecification());

            OfferList.ItemsSource = items;
        }

        protected override bool OnBackButtonPressed() 
        {
            return true;
        }

        async void Handle_ItemSelected(object sender, Xamarin.Forms.SelectedItemChangedEventArgs e)
        {
            var item = e.SelectedItem as Project;
            await Navigation.PushAsync(new SingleOffer(item));
            //OfferList.SelectedItem = null;
        }


    }

Answer 1

So my answer isn't really a good answer, but as "I gave up but found a solution" answer.

I tried to test if NewtonSoft.Json actually worked at all. I tried to do the simplest call you can with this package (turn object into a string). When I did this - and it had nothing to do with my API - it still failed with same error. By doing this I knew it was the package that was something wrong with.

I started a new project, moved my files up and it worked.

Along the way I learned that you don't have to add the reference to NewtonSoft to the native apps, but just the main forms app and potential helper libraries. So not a good and helpful answer, but, well, I've moved on and it works.