Can I open an iPhone TabBar App on a Tab or another depending on Language setted on Device?
For example: First Tab of my app is named "USA", second "Germany", third "France". Is possible to open App directly on second Tab if device's language is setted on German or open App directly on third Tab if device's language is setted on French?
The answer is a definitive "maybe".
As soon as your Default/launch screen disappears you'll end up on the view with the tab bar. You then need to quickly switch to the language/country specific tab programatically, which you should be able to do in UIApplicationDelegate's "application: willFinishLaunchingWithOptions:" delegate method. There's a decent chance the user might see the initial tab view before you do the switch.
You can get the user's preferred language via [NSLocale preferredLanguages].
If you want to get the current country, you'll need to use CLLocationManager.