I’ve recently had the pleasure of porting an iPhone app to the iPad. The process was remarkably easy. This brief article covers the technical issues as well as the relatively minor UI design issues that came up when doing the port.
Apple’s iPhone OS SDK is capable of producing ‘Universal Applications’ which run on multiple devices, including the iPad and iPhone. The recommended approach for existing iPhone app projects is to run an upgrade wizard, which worked beautifully for me. After running the wizard I was initially concerned that nothing happened, because the wizard simply exited with no indication of what occurred — but after comparing project files against the version in my VCS there were obviously some minor changes to the project files, and one new file, the iPad’s main view MainWindow-iPad.xib.
Immediately after running the upgrade wizard I was able to run the app in the iPad simulator. Very impressive. Having implemented the app with relative layouts, the whole UI scaled very nicely to the larger screen. Running through some basic workflows in the app, I expected some things to break — but no, everything worked perfectly!
There were two places in the code where visually things needed adjusting based on the size of the screen. Initially I tried Apple’s recommended approach of conditional coding based on
(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad), however I quickly discovered that it doesn’t work for iPhone 3.1.x apps because
UIUserInterfaceIdiomPad is not defined. Clearly Apple missed something here. After thinking through some creative ways to make this work (see Jeff LaMarche’s blog for an approach that works) I realized that instead of trying to detect the platform, using the screen size was a better approach. An easy way to do that is as follows:
[[UIScreen mainScreen] bounds]
The iPad has some new UI paradigms which are well-described in the iPad HIG. Most apps will benefit from following these guidelines, however I was surprised at how good the app looked in its current form on the iPad.
The moment of truth of course came when I deployed the app to an iPad. Apart from having to download a new provisioning profile from Apple, the process was easy. Within a few minutes it was up and running flawlessly on the device. Kudos go to Apple for making it so easy to port apps from the iPhone to iPad. It’s hard to imagine it being any easier.