iOS developers are quickly updating their apps with Retina graphics to support the new iPad, much like they did two years ago when the iPhone 4 launched. Xcode 4.3.1, the software required to compile Retina iPad apps, launched alongside Apple's new tablet, which gave developers just over a week to prepare their apps for launch on a jarringly high resolution 2048 x 1536 display. This means only a small number of the 200,000 iPad apps have been updated.

So what does it take to get your app ready to go in in hopes of scoring a position in Apple's coveted "Great Apps For The New iPad" section? It turns out that it's not that much work, but you have to be prepared.

Tweetbot developer Paul Haddad told us that most developers found out about the new iPad's Retina display the same time we did — at the iPad launch event. Haddad and designer Mark Jardine spent two days updating the app, which grew in size from 9MB to 25 MB. "It all depends on how much custom UI an app has," Haddad said. "Tweetbot for iPad got three times larger, but Calcbot only doubled in size. It had a number of Retina assets that were already in place for the iPhone." Andrew Stone, developer of Twittelator for iPad, corroborated Haddad's claims. "We just did a massive [doubling] of all the graphics paying attention to any assumptions around the 'scale' of the device. We're pretty ready as developers since we did it when the iPhone 4 came out."

iMovie went from 70MB to just over 400MB

Not all apps are double or even triple the size of their non-Retina counterparts, however. CNET has a nice chart comparing app file sizes (before installation, which are a bit smaller than once they're installed) which illustrates some small increases like how the Kindle app went from 16.6MB (iPad 2) to 18.3 MB (new iPad). The New York Times iPad app went from 4.2 MB to 4.9MB. iMovie went from 70 MB to just over 400 MB, but some new features like a new "trailer" mode have also been added. Oddly enough, Infinity Blade II shrunk from about 941 MB to 791 MB.

An obvious issue with Retina iPad apps is storage. While Apple more than doubled its rule for how large "over the air" downloads can be (from 20 MB to 50 MB), the company did not double internal storage in any new iPad model. In other words, if your 16 GB iPad 2 is filled to the brim with universal apps, you're most likely going to have to ditch a couple once they update to include Retina graphics. And some, you might not be able to download at all anymore over the air. Penultimate developer Ben Zotto told us that developing Retina apps is worrisome because even though Apple raised its limit on over the air downloads, image intensive apps can easily balloon in size. "Most important is that it stays under the cellular download limit so that users are never penalized for not being on Wi-Fi," Zotto said.

Even iPhone users will be forced to download the heavy new apps (assuming they are universal like Infinity Blade II). Haddad told us that "for universal apps [like Calcbot] you are downloading the iPhone and iPad graphics at both 1x and 2x," which can take up a lot of space.

Along with doubling the graphics assets of apps, developers must compile apps using the most recent version of Apple's coding app Xcode, version 4.3.1. This rule has been a barrier to some apps like Instapaper compiled at a higher resolution months ago (in anticipation of a Retina iPad) using the previous version of Xcode, which Apple won't allow. Instapaper won't ship a Retina-compatible version until next week when it's been recompiled using Xcode 4.3.1. "This is slightly embarrassing," Instapaper creator Marco Arment vented on his personal blog. Even if he had finished updating the app two days ago, it likely wouldn't have been ready for launch day.

Downloading new iPad apps onto your iPhone is a giant waste of space, but it's what we're stuck with — and if you're a developer, you're going to design these apps in a week or less. Perhaps at some point in the future, Apple will serve apps individually (even if they're universal) based on what device is downloading them. Until then, we'll just have to keep coughing up space on our iPhones and iPads, and developers will have to keep scrambling during the week before Apple product launches.