A custom UINavigationController that enables the scrolling of the navigation bar alongside the scrolling of an observed content view

• Version 2.x is written as a subclass of UINavigationController, in Swift.
• Version 2.0.0 introduce Swift 2.0 syntax.
• Version 3.0.0 introduce Swift 3.0 syntax.
• Version 4.0.0 introduce Swift 4.0 syntax.
• Version 5.1.0 introduce Swift 4.2 syntax.

If you are looking for the category implementation in Objective-C, make sure to checkout version 1.x and prior, although the 2.x is recomended.

pod 'AMScrollingNavbar'

use_frameworks!

github "andreamazz/AMScrollingNavbar"

Make sure to use ScrollingNavigationController instead of the standard UINavigationController. Either set the class of your UINavigationController in your storyboard, or create programmatically a ScrollingNavigationController instance in your code.

Use followScrollView(_: delay:) to start following the scrolling of a scrollable view (e.g.: a UIScrollView or UITableView).

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    if let navigationController = navigationController as? ScrollingNavigationController {
        navigationController.followScrollView(tableView, delay: 50.0)
    }
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    [(ScrollingNavigationController *)self.navigationController followScrollView:self.tableView delay:0 scrollSpeedFactor:1 collapseDirection:NavigationBarCollapseDirectionScrollDown followers:nil];
}

Use stopFollowingScrollview() to stop the behaviour. Remember to call this function on disappear:

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)

    if let navigationController = navigationController as? ScrollingNavigationController {
        navigationController.stopFollowingScrollView()
    }
}

To DRY things up you can let your view controller subclass ScrollingNavigationViewController, which provides the base setup implementation. You will just need to call followScrollView(_: delay:):

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    if let navigationController = navigationController as? ScrollingNavigationController {
        navigationController.followScrollView(tableView, delay: 50.0)
    }
}

To move another view, like a toolbar, alongside the navigation bar you can provide the view or multiple views as the followers parameter. Since you might want to have the follower up or down, you'll have to specify the scroll direction of the view once it starts to follow the navigation bar:

if let navigationController = navigationController as? ScrollingNavigationController {
    navigationController.followScrollView(tableView, delay: 50.0, followers: [NavigationBarFollower(view: customFooter, direction: .scrollDown)])
}

Note that when navigating away from the controller the followers might keep the scroll offset. Refer to Handling navigation for proper setup.

If you want to furhter scroll the navigation bar out of the way, you can use the optional parameter additionalOffset in the followScrollView call.

You can also pass a UITabBar in the followers array:

if let navigationController = navigationController as? ScrollingNavigationController {
    navigationController.followScrollView(tableView, delay: 50.0, followers: [tabBarController.tabBar])
}

You can set a delegate to receive a call when the state of the navigation bar changes:

if let navigationController = navigationController as? ScrollingNavigationController {
    navigationController.scrollingNavbarDelegate = self
}

Delegate function:

func scrollingNavigationController(_ controller: ScrollingNavigationController, didChangeState state: NavigationBarState) {
    switch state {
    case .collapsed:
        print("navbar collapsed")
    case .expanded:
        print("navbar expanded")
    case .scrolling:
        print("navbar is moving")
    }
}

If the view controller with the scroll view pushes new controllers, you should call showNavbar(animated:) in your viewWillDisappear(animated:):

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    if let navigationController = navigationController as? ScrollingNavigationController {
      navigationController.showNavbar(animated: true)
    }
}

When the user taps the status bar, by default a scrollable view scrolls to the top of its content. If you want to also show the navigation bar, make sure to include this in your controller:

func scrollViewShouldScrollToTop(_ scrollView: UIScrollView) -> Bool {
    if let navigationController = navigationController as? ScrollingNavigationController {
        navigationController.showNavbar(animated: true)
    }
    return true
}

You can control the speed of the scrolling using the scrollSpeedFactor optional parameter:

controller.followScrollView(view, delay: 0, scrollSpeedFactor: 2)

Check out the sample project for more details.

Andrea Mazzini. I'm available for freelance work, feel free to contact me.

Want to support the development of these free libraries? Buy me a coffee ☕️ via Paypal.

Syo Ikeda and everyone kind enough to submit a pull request.

The MIT License (MIT)

Copyright (c) 2018 Andrea Mazzini

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
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the Software, and to permit persons to whom the Software is furnished to do so,
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