Hi,
I’m making adjustments to my app in preparation for sending it to iTunes Connect. Wish me luck.

I want to understand density mapping with regards to png images used for my button icons. I have a series of pngs that are 48x48 pixels. I have imported them into a substack and sized them to 30x30 and referenced them. This is what I think I'll need to adjust. My question is, being this will be for iPhone, what size files will I need? Do I need all four medium, high, extra-high and ultra-high or has this changed? Thanks for help.
imageName@medium.png 30x30
imageName@high.png 45x45
imageName@extra-high.png 60x60
imageName@ultra-high.png 120x120