try to use app delegate:
UISplitViewController *split = [self.storyboard instantiateViewControllerWithIdentifier:@"orders_split"];
MyAppDelegate *appDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
appDelegate.window.rootViewController = split;
in my projects I do it with animation:
+(void)setRootController:(UIViewController*)controller
storyboard:(UIStoryboard*)storyboard{
MyAppDelegate *appDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
[UIView
transitionWithView:appDelegate.window
duration:0.5
options:UIViewAnimationOptionTransitionCrossDissolve
animations:^(void) {
BOOL oldState = [UIView areAnimationsEnabled];
[UIView setAnimationsEnabled:NO];
appDelegate.window.rootViewController = controller;
[UIView setAnimationsEnabled:oldState];
}
completion:nil];
}