switch between view controllers without segues

appDelegate.h

/*
** in your header, define a reference
*/
- (void)switchViewController:(UIViewController*)view :(NSString*)segue;

appDelegate.m

/*
** somewhere in your app delegate
** if you feel brave, create a UIViewController category and link to it
** ex: UIViewController+switcher.h
*/
- (void)switchViewController:(UIViewController*)view :(NSString*)segue
{
    NSString * name = @"Main";
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:name bundle: nil];
    UIViewController *viewcontroller = [storyboard instantiateViewControllerWithIdentifier:segue];
    [view presentViewController:viewcontroller animated:nil completion:nil];
}

viewController.h

@property (strong, nonatomic) AppDelegate* delegate;
- (IBAction)openMenu:(id)sender;

viewController.m

#import "AppDelegate.h"

/*
** inside viewDidLoad
*/
_delegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];


/*
** somewhere in your storyboard is a view controller 
** with a Storyboard ID of menuViewController in this example
*/
- (IBAction)openMenu:(id)sender {
    NSString *segue = @"menuViewController";
    [_delegate switchViewController:self :segue ];
  }