Ion-infinite-scroll and an instagram like pull down for new content


I read the document on ion-infinite-scroll but I could not understand how it works! Do I need to concat my new result to my older $scope.items or should I empty it and push all my new items in the empty $scope.items?

My second question is about fetching new contents from the server. If you have worked with instagram you know that when pulling the page down you can load new content. How can I do such a thing using Ionic?