Sharepoint Hosted App : Loop through all list items using site workflow

I have to iterate through all list items for specific list using site workflow in sharepoint hosted app. My list is on app web.Based on Task Status column value of each list item ,I have to send email to assigned user.But I can't found any way to iterate all list item. I can't use rest API, because list is on app web. Please suggest me, how could I achieve this?

Thanks