Call rest api and show data to view in xamarin

First conver the end json result your will get in to c# method.
Like :

[{
  "userId": 1,
  "id": 1,
  "title": "delectus aut autem",
  "completed": false
}]

Go to the http://json2csharp.com/ and paste it , you will then get the method of it.

Then make Products.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace App5
{
    class Products
    {
        public int userId { get; set; }
        public int id { get; set; }
        public string title { get; set; }
        public bool completed { get; set; }
    }
}

MainPage.xaml

<ListView x:Name="ProductsListView">
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <StackLayout Orientation="Horizontal">
                        <Label Text="{Binding title}" TextColor="Black"></Label>
                        <Label Text="{Binding completed}" TextColor="Black"></Label>
                    </StackLayout>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>

MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using System.Net.Http;
using Newtonsoft.Json;

namespace App5
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();

            GetProducts();
        }
        private async void GetProducts()
        {
            HttpClient client = new HttpClient();
            var response = await client.GetStringAsync("https://jsonplaceholder.typicode.com/todos/");
            var products=JsonConvert.DeserializeObject<List<Products>>(response);
            ProductsListView.ItemsSource = products;
        }
    }
}