ListView LoadMore Xamarin

Hello, guys.

I need to get my data to be loaded gradually in a listview, searching a little I found a material on the ListViewCachingStrategy, however, it is difficult to adapt my need, no example matches what I really need. Come on, I have an api with the following class:

public class Category
{
  public int CategoryId { get; set; }
        public string Description { get; set; }
        public string Image { get; set; }
        public string Tags { get; set; }
}
 public class Product
    {   
        public int ProductId { get; set; }

        public int CategoryId { get; set; }

        public Category Category { get; set; }

        public string Description { get; set; }
}

To consume the data and display I obviously use a list:

 List<Category> categories;

The problem is that I load products from a category (subclass), I could not control the loading of items, when I open the application it gets stuck until I can load all the data in the list view, I accept any suggestion for to solve the problem (even codebehind), I'm using xamarin forms in visual studio 2017.