HomeTableViewController.m

- (IBAction)btnLogout:(id)sender {
    
    TabBarViewController *tabBarViewControllerObj = [[TabBarViewController alloc] init];
    [Lockbox setString:@"FALSE" forKey:kLoggedinStatusKeyString];
    [tabBarViewControllerObj loginCheck];
}

TabBarViewController.h

#import <UIKit/UIKit.h>

@interface TabBarViewController : UITabBarController

- (void)loginCheck;

@end

TabBarViewController.m

- (void)loginCheck
{
    UIStoryboard *mainstoryboard = self.storyboard;
    LoginViewController* loginViewController = [mainstoryboard instantiateViewControllerWithIdentifier:@"LoginViewController"];
    
    if ([[Lockbox stringForKey:kLoggedinStatusKeyString] isEqualToString:@"FALSE"]) {
        [self presentViewController:loginViewController animated:NO completion:nil];
    }
}