language change only after restart on iphone

I'm trying to change app language, but when I run this code in main.h language chages after I shut down an App and run it again. Is this possible to change language without restarting?

int main(int argc, char *argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    NSArray *languages = [NSArray arrayWithObject:@"en_GB"];
    [[NSUserDefaults standardUserDefaults] setObject:languages forKey:@"AppleLanguages"];
    [[NSUserDefaults standardUserDefaults] synchronize];

    int retVal = UIApplicationMain(argc, argv, nil, nil);
    [pool release];
    return retVal;
}