Basic API Call for Xamarin.Forms

APIService.cs

public class APIService
{
    HttpClient client;

    public APIService()
    {
        client = new HttpClient();
        client.MaxResponseContentBufferSize = 256000;
    }

    /// <summary>
    /// Get all todo data from dummy API
    /// </summary>
    /// <returns></returns>
    public async Task<List<TodoResponse>> GetAllToDo()
    {
        // Change to desired URL.
        string restUrl = "https://jsonplaceholder.typicode.com/todos";

        var uri = new Uri(restUrl);
        var response = await client.GetAsync(uri);
        if (response.IsSuccessStatusCode)
        {
            var content = await response.Content.ReadAsStringAsync();
            var result = JsonConvert.DeserializeObject<List<TodoResponse>>(content);
            return result;
        }
        return null;
    }

    /// <summary>
    /// Get all todo data from dummy API (Raw JSON format)
    /// </summary>
    /// <returns></returns>
    public async Task<string> GetAllToDoRaw()
    {
        // Change to desired URL.
        string restUrl = "https://jsonplaceholder.typicode.com/todos";

        var uri = new Uri(restUrl);
        var response = await client.GetAsync(uri);
        if (response.IsSuccessStatusCode)
        {
            var content = await response.Content.ReadAsStringAsync();
            return content;
        }
        return null;
    }
}

/// <summary>
/// JSON result as class
/// </summary>
public class TodoResponse
{
    public int UserId { get; set; }
    public int Id { get; set; }
    public string Title { get; set; }
    public bool Completed { get; set; }
}