How to enable back/left swipe gesture in UINavigationController after setting leftBarButtonItem?

First set delegate in viewDidLoad:

self.navigationController.interactivePopGestureRecognizer.delegate = self;

And then disable gesture when pushing:

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    [super pushViewController:viewController animated:animated];
    self.interactivePopGestureRecognizer.enabled = NO;
}

And enable in viewDidDisappear:

self.navigationController.interactivePopGestureRecognizer.enabled = YES;

Also, add UINavigationControllerDelegate to your view controller.

You need to handle two scenarios:

1. When you're pushing a new view onto the stack
2. When you're showing the root view controller

If you just need a base class you can use, here's a Swift 3 version:

import UIKit

final class SwipeNavigationController: UINavigationController {
    
    // MARK: - Lifecycle
    
    override init(rootViewController: UIViewController) {
        super.init(rootViewController: rootViewController)

         delegate = self
    }
    
    override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
        
        delegate = self
    }

    required init?(coder aDecoder: NSCoder) { 
        super.init(coder: aDecoder) 

        delegate = self 
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // This needs to be in here, not in init
        interactivePopGestureRecognizer?.delegate = self
    }
    
    deinit {
        delegate = nil
        interactivePopGestureRecognizer?.delegate = nil
    }
    
    // MARK: - Overrides
    
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        duringPushAnimation = true
        
        super.pushViewController(viewController, animated: animated)
    }
    
    // MARK: - Private Properties
    
    fileprivate var duringPushAnimation = false

}

// MARK: - UINavigationControllerDelegate

extension SwipeNavigationController: UINavigationControllerDelegate {
    
    func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
        guard let swipeNavigationController = navigationController as? SwipeNavigationController else { return }
        
        swipeNavigationController.duringPushAnimation = false
    }
    
}

// MARK: - UIGestureRecognizerDelegate

extension SwipeNavigationController: UIGestureRecognizerDelegate {
    
    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        guard gestureRecognizer == interactivePopGestureRecognizer else {
            return true // default value
        }
        
        // Disable pop gesture in two situations:
        // 1) when the pop animation is in progress
        // 2) when user swipes quickly a couple of times and animations don't have time to be performed
        return viewControllers.count > 1 && duringPushAnimation == false
    }
}

If you end up needing to act as a UINavigationControllerDelegate in another class, you can write a delegate forwarder similar to this answer.

Adapted from source in Objective-C: https://github.com/fastred/AHKNavigationController

It works for me when I set the delegate

self.navigationController.interactivePopGestureRecognizer.delegate = self;

and then implement

Swift

extension MyViewController:UIGestureRecognizerDelegate {
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldBeRequiredToFailBy otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
}

Objective-C

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}