Which open source licenses are compatible with the Apple's iPhone and its official App Store ?

I don't think LGPL will work for iPhone applications.

The problem is that the iPhone runtime does not allow you to bundle shared libraries (or frameworks) with your app. Only single binary applications are allowed. The LGPL is based on the assumption that you bundle a shared library with an application. Direct linking is still forbidden.

This is not legal advice, I am not a lawyer, but it sounds like you need a library with a BSD or Apache license. That would be the case if you were developing a proprietary desktop program that used an open source library. I don't know if Apple has any further restrictions for iPhone apps.

(I am not a lawyer.)

Static object file linking may address the question of how to allow an app which uses LGPL licensed code to be made available without distributing the non-LGPL'd portions of its source code.

But it seems like LGPL, as a variant on GPL, imposes a larger insurmountable problem for iPhone app development in that the development tools needed to create and distribute any iPhone app are only available under terms from Apple that are incompatible with GPL. ie. There is a $100/year fee, and there are numerous terms and conditions on the use of those tools that are not part of the GPL license. The terms of the license for Apple's iPhone developer tools seem to be incompatible with the spirit of and perhaps also the letter of GPL.

If you're not releasing your source code, you can't use any strict copyleft license. You can't use any GPLv3-based license in any case, since the iPhone distribution conflicts with the no-Tivoization clause.

If you're using LGPLv2, you'll have to provide your program in linkable format, which may or may not be acceptable (at least it's not source code), and this is likely to be something you don't want to deal with, unless the library offers a lot of benefit.

If there's one copyright holder on the library, you can always see if you can get a license exception.

You won't have any problem with the typical BSD/MIT/Boost/whatever permissive licenses. There are a lot of Open Source/Free Software licenses out there, and for the rest you'll have to read them and see.

When I try to port Fuego onto iPhone, I asked a similar question on the fuego mailing list. So far, my understanding is "LGPL is not compatible with AppStore". A previous question also receives an answer as: no.