Since I had to fix my application icon file I thought I would take a look at what additional icon and image files the iPad and iPhone OS 3.2 introduced and create those at the same time. Some of the new icons are optional but even so the list is longer than I thought. It is even longer if you consider ever image you need to produce to submit a finished app to the App Store:

Application Icons

• Icon.png (57 x 57 pixels) - iPhone and iPod Touch
• Icon-ipad.png (72 x 72 pixels) - iPad

The application icons are displayed on the device home screen. Pre-3.2 there was a single application icon file named Icon.png that needed to be a 57 x 57 pixel png file. The name of the file is set in the Info.plist file for the application using the CFBundleIconFile key. With the release of iPhone OS 3.2 there is now also a larger icon file (72 x 72 pixels) for the iPad. If you are creating a Universal app for iPhone, iPod and iPad devices both these filenames would be listed using the CFBundleIconFiles key in Info.plist.

Small Icons

The small icons are used to whenever the application matches a Spotlight search or if the application is using the built-in Settings application. These icons are optional as the application icon will be scaled down and used when necessary.

• Icon-Small-50.png (50 x 50 pixels) - iPad
• Icon-Small.png (29 x 29 pixels) - iPhone and iPod Touch

Large Application Icon

When submitting an app to the App Store you need a 512 x 512 pixel version of the application icon. This image can be in TIFF or JPEG format. It is not normally part of the application bundle except for when you want to create an Ad Hoc distribution. In that case it needs to be placed in the root of the application bundle and named iTunesArtwork (with no file extension).

• logo.tiff (512 x 512 pixels) - for App Store only (name and format can vary)
• iTunesArtwork (512 x 512 pixels) - for Ad Hoc distributions only

Launch Images

The launch image is what gets displayed automatically by the OS whilst your application is loading. Pre-3.2 this was a single file named Default.png 320 x 480 pixels in dimension. With the iPad allowing applications to launch in any orientation this gets much more complicated:

• Default.png (320 x 480 pixels) - iPhone and iPod Touch
• Default-Portrait.png (768 x 1004 pixels) - iPad
• Default-Landscape.png (1024 x 748 pixels) - iPad
• Default-PortraitUpsideDown.png (768 x 1004 pixels) - iPad, if missing Default-Portrait.png is used.
• Default-LandscapeLeft.png (1024 x 748 pixels) - iPad, if missing Default-Landscape.png is used.
• Default-LandscapeRight.png (1024 x 748 pixels) - iPad, if missing Default-Landscape.png is used.

Device Specific Keys

Whilst that covers the most common image files that will be needed it is not quite the end of the story. With iPhone OS 3.2 Apple has introduced the concept of device specific keys. This means that you can override the keys in the Info.plist file for each device. The basic format of the key is now:

key_root-<platform>~<device>

The <platform> is optional and can be discarded as it can currently only take the value iphoneos. The <device> portion though can take one of three possible values: iphone, ipod or ipad. This means that you can start to define images specific to a device.