How to manage different background image sizes for different ios devices

how to manage different background image sizes for different ios devices using ionic framework

Background image sizes in your template views? As in the CSS property background-image?

How about using background-size: 100% or background-size: cover
http://www.w3schools.com/cssref/css3_pr_background-size.asp

If that isn’t what you mean, please be more specific when you ask your question. It shows respect to the reader.