Handle long press on a single UITabBarItem

Here's how I did it using Swift 3:

protocol MyTabControllerProtocol: class {
    func tabLongPressed()
}

class MyTabController: UITabBarController {
    func viewDidLoad() {
        super.viewDidLoad()

        viewControllers = [
            // add your view controllers for each tab bar item
            // NOTE: if you want view controller to respond to long press, then it should extend MyTabControllerProtocol
        ]

        let longPressRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(astroButtonItemLongPressed(_:)))
        tabBar.addGestureRecognizer(longPressRecognizer)
    }

    func astroButtonItemLongPressed(_ recognizer: UILongPressGestureRecognizer) {
        guard recognizer.state == .began else { return }
        guard let tabBar = recognizer.view as? UITabBar else { return }
        guard let tabBarItems = tabBar.items else { return }
        guard let viewControllers = viewControllers else { return }
        guard tabBarItems.count == viewControllers.count else { return }

        let loc = recognizer.location(in: tabBar)

        for (index, item) in tabBarItems.enumerated() {
            guard let view = item.value(forKey: "view") as? UIView else { continue }
            guard view.frame.contains(loc) else { continue }

            if let nc = viewControllers[index] as? UINavigationController {
                if let vc = nc.viewControllers.first as? MyTabControllerProtocol {
                    vc.tabLongPressed()
                }
            } else if let vc = viewControllers[index] as? MyTabControllerProtocol {
                vc.tabLongPressed()
            }

            break
        }
    }
}

You can subclass UITabBarController and add a UILongPressGestureRecognizer to it's tabBar. Acting as the delegate of the gesture recognizer will allow you to be selective over when it will detect a long press. Since the tab bar item will be selected as soon as the user touches it you can use the selectedItem property to perform this check.

@interface TabBarController () <UIGestureRecognizerDelegate>
@property (nonatomic, strong) UILongPressGestureRecognizer *longPressRecognizer;

@end

@implementation TabBarController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.longPressRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(recognizerFired:)];
    self.longPressRecognizer.delegate = self;
    [self.tabBar addGestureRecognizer:self.longPressRecognizer];
}

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {

    // This will ensure the long press only occurs for the
    // tab bar item which has it's tag set to 1.
    // You can set this in Interface Builder or in code
    // wherever you are creating your tabs.
    if (self.tabBar.selectedItem.tag == 1) {
        return YES;
    }
    else {
        return NO;
    }

}

- (void)recognizerFired:(UILongPressGestureRecognizer *)recognizer {
    // Handle the long press...
}

@end

I did this by getting the specific tabBarItem's view that user can interact and simply added the long press gesture to that. With that way you do not have to write any protocols or subclass the TabBarViewController.

let longPressGestureRecognizer = UILongPressGestureRecognizer.init(target: self, action: #selector(longTap(_:)))
    longPressGestureRecognizer.minimumPressDuration = 1.0
    self.tabBarController?.orderedTabBarItemViews()[0].addGestureRecognizer(longPressGestureRecognizer)

And as for getting the tabBarItemViews :

extension UITabBarController {
func orderedTabBarItemViews() -> [UIView] {
    let interactionViews = tabBar.subviews.filter({$0.isUserInteractionEnabled})
    return interactionViews.sorted(by: {$0.frame.minX < $1.frame.minX})
}

P.S. : The viewController, namely "self" is the first item for the tabBarController.