I have a pair of GPL apps on the AppStore myself (one of which, Eat the Whistle, is not free), but if you want to build a closed source app it may be problematic.
LGPL requires dynamic linkage, or object code redistribution, you cannot dynamic link libraries not present in the iOS sdk on the Apple App Store, or your app is rejected.
So you can publish to the App Store, but only if you build an opensource app, or if you distribute the object files for "relink" (not practical nor acceptable for closed source stuff).
There are a few well-known opensource libraries that, given this restriction, made a "mobile platform" exception to their licensing.
Other, like SDL, moved from LGPL to BSD.