Apple’s new iOS7 means app will need to be visually tweaked to match new fonts, grids, and colors – it’s something designers are all thinking about or just avoiding. For those who still have a lot of legwork to do, I’ve discovered this amazing cheat sheet with all of the necessary information from the pixel ratios of each device to the new iconography styling.
Something to keep in mind about the new icon grid:
Apple developed a golden ratio grid system, which can be used to size and align elements on your icon correctly. Anyways, the grid template got criticized a lot by the design community, and it seems like designers (even Apple designers) are not following the grid system very strictly. Feel free to break rules if your icon looks better without taking care of the new grid system.