I'm not sure, but I would be very surprised indeed if you were allowed to use the apple logo within an app without direct permission. If I would you, I would contact them and ask for any permission and requirements for such a request. Chances are though that they will reject the request.
As I said, I'm not sure, but contact them anyway.
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Just found this
2. Compatibility: Developers may use Apple, Macintosh, iMac, or any other Apple word mark (but not the Apple Logo or other Apple-owned graphic symbol/logo) in a referential phrase on packaging or promotional/advertising materials to describe that the third party product is compatible with the referenced Apple product or technology, provided they comply with the following requirements.
a. The Apple word mark is not part of the product name.
b. The Apple word mark is used in a referential phrase such as runs on, for use with, for, or compatible with.
c. The Apple word mark appears less prominent than the product name.
d. The product is in fact compatible with, or otherwise works with, the referenced Apple product.
e. The reference to Apple does not create a sense of endorsement, sponsorship, or false association with Apple or Apple products or services.
f. The use does not show Apple or its products in a false or derogatory light.
Heres a link to apples information:
http://www.apple.com/legal/trademark/guidelinesfor3rdparties.html
Hope this helps.