By default, when building an application with Xcode, your icon will have a round beveling of the corners and a shine added over the top of the icon. The icon below shows how this looks:

You can override this default by following line to you to the Info.plist file. For example, if you prefer to edit Info.plist as a source file, add the following line:

If you are editing Info.plist as an XML file (in Xcode) you can add an entry that looks as follows:

Depending on your configuration and version of Xcode, the option in the Info.plist file may looks as follows:

With the pre-rendered icon set to true, the icon shown above will now look like this:

This preference setting only applies to removing of the shine / glossy effect, the corners of your icon will still be rounded for you.

(추가)

위 내용은 아이콘 제작을 다른 사람이 해주는 경우(디자이너 등) 반사 효과 등을 넣은 상태로 받게 되었을 경우 등에 유용합니다.

This artice may be a good tip for icon which is not your willing. (designer or someone adds gloss effects)