As a beginner iOS developer can do a sane design an Iphone app?

I can tell only the literature, quite interesting and informative:
Alan Cooper "the mental hospital in the hands of patients"
There's quite interesting describes an approach to designing human interaction with the device.
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But with regards to what buttons are not prompt.

Sets there. Depending on what you need are around 5 to 40 bucks. Much useful knowledge of Photoshop. Photoshop with friends is mastered for a month or two. First examine the ideology of layers (layers) and style (Photoshop styles).
Button sets some — www.shutterstock.com/
But it is much better to use sets: www.splashnology.com/article/60-free-ui-design-kits-templates-and-resources/853/ select the style and buttons make your own (find the first link).
In any case, it is not a quick process — if you do it yourself

Can be inspired by the design of other applications pttrns.com