关于Icon.png设置的官方文档

http://developer.apple.com/library/ios/#qa/qa1686/_index.html

App Icons on iPad and iPhone

Q: How are the icon files in my application bundle used on iPad and iPhone?

A: How are the icon files in my application bundle used on iPad and iPhone?

Below are guidelines for handling icon files for iPhone-only apps, iPad-only apps, and universal apps.

Important: Icons marked with "Required" must be supplied in your application bundle.

iPhone-only Apps

Include the following in your application's Resources group in the Xcode project:

Table 1  iPhone-only apps icon requirements.

Image Size (px)	File Name	Used For	Required Status	Notes
512x512	iTunesArtwork	Ad Hoc iTunes	Optional but recommended	File should be in png format, but name it without the .png extension
57x57	Icon.png	App Store and Home screen on iPhone/iPod touch	Required
114x114	Icon@2x.png	Home screen for iPhone 4 High Resolution	Optional but recommended
72x72	Icon-72.png	Home screen for iPad compatibility	Optional but recommended
29x29	Icon-Small.png	Spotlight and Settings	Optional but recommended
50x50	Icon-Small-50.png	Spotlight for iPad compatibility	Recommended if you have a Settings bundle, otherwise optional but recommended
58x58	Icon-Small@2x.png	Spotlight and Settings for iPhone 4 High Resolution	Recommended if you have a Settings bundle,  otherwise optional but recommended

Your Resources group should look similar to Figure 1:

Except for iTunesArtWork icon, list the names of each of these files in the Icon files entry in theInfo.plist, in the order shown in the table. Follow the steps in "Add Icon files in Info.plist" section below. See Figure 4.

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Add Icon files in Info.plist

To add the Icon files entry you will need to manually edit your Info.plist.

Open your Info.plist in Xcode, and locate the "Icon file" entry. Click on the plus (+) button at the end of the entry to make a new key entry. as shown in Figure 2.

Figure 2  Add a new entry under "Icon file" key

Then, type "Icon files" in the key column (notice the "s" added), or choose "Icon files" from the drop down list, as shown in Figure 3.

Figure 3  Add "Icon files" key in Info.plist

Next, turn down the disclosure triangle on "Icon files" and add the entries for the icons for your application, as shown in Figure 4 and Figure 5:

Figure 4  Add icon file entries for iPhone-only or Universal apps.

Figure 5  Add entries for iPad icon files.

Note: If you don't provide one of the listed optional icons, the system will automatically scale one of your existing icons to an appropriate size. However, it is strongly recommended that your application supply all the icons listed with specific sizes needed.

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