A Lithuanian developer, LemonLabs, has recently published an interesting infographic detailing a few simple ways in which designers can prepare their assets for developers in a useful and sensible way. The advice ranges from simple standard resolutions for icons, to highlighting particular Apple style guidelines, and how to package your final bundle of assets. A lot of it seems like common sense, but I'm sure there are at least a few iOS developers out there who would like to make sure their designers have at least glanced over something like this.
If you're an avid listener of Iterate, our mobile design podcast -- and if you aren't, hurry up and start listening now! -- you know the subject of how designers pass of assets to developers is rather hotly contested. Some designers want complete control over final image files, right down to the slice, while others think it's the developers job to take the Photoshop or Fireworks source file and cut it up themselves. Likewise, some developers have no idea how to edit an image and just want the slices all pretty and packaged, while other developers want final control to the point of preferring to slice the source files themselves.
When you factor in managing Retina (@2x) and non-retina assets, making sure everything is pixel perfect can become both an art and a chore. Luckily, compared to other platform, Apple's small set of screen sizes makes the task at least somewhat manageable. (iOS developers don't have to invent their own forms of antialiasing and test against different screen technologies, for example!)
So consider this a cheat-sheet, or a funny way to make a much-needed point.
And for way more on the topic of mobile design, keep listing to Iterate and check out our Mobile Design & Development Forum!