For
an iPhone app compiled for iOS 3.1.3 or an earlier version, you were
required to include a 57-by-57-pixel app icon and a default launch
image sized for portrait orientation in your Xcode project. With iOS
3.2 and the iPad's support for multiple orientations, the project
images that an iPad app or a universal application requires are much
different.
1. App Icon Images
Beyond the usual
512-by-512-pixel app icon that's required by the App Store, you'll need
to add the following iPad icon files to your Xcode project's Resources
folder:
72-by-72-pixel PNG image: The app icon displayed on the iPad's home screen.
50-by-50-pixel PNG image:
The app icon shown if your app name is listed in iPad Spotlight Search
results. It's important to note that iOS crops 1 pixel from all sides
of this icon, so only the inner 48 by 48 pixels are displayed.
29-by-29-pixel PNG image: This app icon is required only if your application places settings options in iOS Settings app.
Don't worry about the
rounded edges and glossy beveled look that iPad app icons typically
have. iOS and the App Store automatically add those elements to the
icon for you. Although you can't do anything about the dynamically
added rounded edges, you do have the option to disable the default
beveled gloss effect from your app icon if your app icon looks better
without it.
After you've added your
72-by-72-pixel icon PNG file to the Resources folder of your iPad app
project in Xcode, you'll need to open your project's plist
file. Once you've added the icon's filename to the Icon property, click
the gray plus symbol (+) button on the bottom-right side of the list to
add a new entry to the plist file. In
the new, blank row, click the tiny arrows in the left Key column to
display a contextual menu of additional properties. Select Icon already includes gloss and bevel effects from that menu. Setting its value to True will disable the default beveled gloss effect from your app icon, as shown in Figure 1.
When displaying your 72-by-72-pixel app icon on the iPad or the
512-by-512-pixel icon in the App Store, Apple checks your app's plist file first, so your preferred setting is always honored.
2. Document Type Icon Images
If your iPad app utilizes
the new Document Support feature and registers a custom file type with
the iOS registry, you should assign a custom document icon to it, so
that users can visually identify that file type as belonging to your
app.If you don't assign a custom icon to your app's file type, iOS will
display your app icon inside a white document (with a top-right corner
page curl). Most apps simply rely on that system default, but if you
would prefer to design your own document icon, you'll need to save your
custom icon in two sizes: a 64-by-64-pixel PNG image and a
320-by-320-pixel PNG image.
Do not design your icon
to emulate a document with a page curl. iOS automatically adds the
document border, drop shadow, and top-right corner page curl. Due to
these system-supplied graphics effects, you must take special care to
place your icon's main imagery within the "safe zone" area. For the
64-by-64-pixel icon, stay within 1 pixel from the top, 4 pixels from
the bottom, and 10 pixels from both sides. For the 320-by-320-pixel
icon, stay within 5 pixels from the top, 20 pixels from the bottom, and
50 pixels from both sides.
3. Default Launch Images
A launch image is briefly
displayed on the screen when an app is first loading. This means the
image should represent only the basic user interface elements of the
app's initial window. For example, if your app's first screen shows a
split view controller, then your default launch image should reflect
the same controller layout, without any text or any content.
On the iPhone, your app needed to provide only a single portrait orientation image named Default.png.
But on the iPad, Apple wants your app to support multiple orientations.
Since a user could launch your iPad app in any orientation, your Xcode
project will need to include multiple default launch images. Even
though the iPad screen is 768 pixels by 1024 pixels, the launch images
should not include the status bar, which accounts for the top 20 pixels.
The Default filename is still employed, but the orientation label is appended to the name with a hyphen, as follows:
Default-Portrait.png: This 768-by-1004-pixel image represents the first view in portrait orientation.
Default-PortraitUpsideDown.png: Unless your initial portrait window is different if viewed upside down, this image is not needed. In its absence, Default-Portrait.png will be shown.
Default-Landscape.png: This 1024-by-748-pixel image represents the first view in landscape orientation.
Default-LandscapeLeft.png and Default-LandscapeRight.png:
Unless your initial landscape window is different depending on whether
the device is rotated left or right, these images are not needed. In
the absence of either (or both) of these images, Default-Landscape.png will be shown.
If you're building a universal
application, you'll need to designate unique prefixes to your launch
image filenames, so that your Xcode project can properly identify which
PNG files to use for the iPhone and the iPad, respectively. This is
configured via the UILaunchImageFile key in your app's plist file. In order to differentiate between the two platforms, attach a device-specific value to the UILaunchImageFile key title, connected with a tilde character (no spaces). The UILaunchImageFile~iphone key's string is for the iPhone, so it would remain as Default. You would use a different iPad-related name for the UILaunchImageFile~ipad key's string, such as iPadDefault. In the universal application's plist file, the key-string syntax would look like this:
<key>UILaunchImageFile~iphone</key>
<string>Default</string>
<key>UILaunchImageFile~ipad</key>
<string>iPadDefault</string>
With these plist
keys in place, you then want your launch image filenames to adhere to
that assigned prefix. For example, your iPad launch images would be
named iPadDefault-Portrait.png, iPadDefault-Landscape.png, and so on. Your iPhone launch image would remain Default.png.
