Creating a Slide Down Menu Using View Controller Transition

Navigation is an important part of every user interface. There are multiple ways to present a menu for your users to access the app’s features. The sidebar menu that we discussed in the earlier tutorial is an example. Slide down menu is another common menu design. When a user taps the menu button, the main screen slides down to reveal the menu. If you have no idea about how a slide-down menu works, no worries. Just read on and you’ll see an animated demo.

Before showing you how to implement the menu, this tutorial assumes that you have a basic understanding of custom view controller transition. For those who are new to view controller transition, you can check out this beginner tutorial written by Joyce.

Okay, let’s get started.

A Quick Demo of Slide Down Menu

In this tutorial, we will build a slide down menu in Swift. Here is a quick demo of what you’re going to implement:


The Project Template

As usual, I don’t want you to start from scratch. You can download the project template here. It includes the storyboard and view controller classes. You will find two table view controllers. One is for the main screen (embedded in a navigation controller) and the other is for the navigation menu. If you run the project, the app should present you the main interface with some dummy data.

Before moving on, take a few minutes to browse through the code template to familiarize yourself with the project.


Presenting the Menu Modally

First, open the Main.storyboard file. You should find two table view controllers, which are not connected with any segue yet. In order to bring up the menu when a user taps the menu button, control-drag from the menu button to the menu table view controller. Release the buttons and select “present modally” under action segue.


If you run the project now, the menu will be presented as a modal view. In order to dismiss the menu, we will add an unwind segue.

Open the NewsTableViewController.swift file and insert an unwind action method:

Next, go to the storyboard. Control-drag from the prototype cell of the Menu table view controller to the exit icon. When prompted, select the unwindToHome: option under selection segue.

slide down menu - connect outlet

Now when a user taps any menu item, the menu controller will dismiss to reveal the main screen. Through the unwindToHome: action method, the main view controller (i.e. NewsTableViewController) retrieves the menu item selected by the user and changes its title accordingly. To keep things simple, we just change the title of the navigation bar and will not alter the content of the main screen.

In addition, the menu controller will highlight the currently selected item in white. There are a couple of methods we need to implement before the app can work as expected.

Insert the following method in the MenuTableViewController class:

Here, we just set the currentItem to the selected menu item.

In the NewsTableViewController.swift file, insert the following method to pass the current title to the menu controller:

Now compile and run the project. Tap the menu item and the app will present you the menu modally. When you select a menu item, the menu will dismiss and the navigation bar title will change accordingly.

Slide down menu

Creating the animated Slide Down Menu

Now that the menu is presented using the standard animation, let’s begin to create a custom transition. As I mentioned in the previous chapter, the core of custom view controller animation is the animator object, which conforms to both UIViewControllerAnimatedTransitioning and UIViewControllerTransitioningDelegate protocols. We are going to implement the class, but first, let’s take a look at how the slide down menu works. When a user taps the menu, the main view begins to slide down until it reaches the predefined location, which is 150 points away from the bottom of the screen. The below illustration should give you a better idea of the sliding menu.


Building the Slide Down Menu Animator

To create the slide down effect, we will create a slide down animator called MenuTransitionManager. In the project navigator, right click to create a new file. Name the class MenuTransitionManager and set it as a subclass of NSObject.

Update the class like this:

The class implements both UIViewControllerAnimatedTransitioning and UIViewControllerTransitioningDelegate protocols. I will not go into the details of the methods, as they are explained in the previous chapter. Let’s focus on the animation block (i.e. the animateTransition method).

Referring to the illustration displayed earlier, during the transition, the main view is the fromView, while the menu view is the toView.

To create the animations, we configure two transforms. The first transform (i.e. moveDown) is used to move down the main view. The other transform (i.e. moveUp) is configured to move up the menu view a bit so that it will also have a slide-down effect when restoring to its original position. You will understand what I mean when you run the project later.

From iOS 7 and onwards, you can use the UIView-Snapshotting API to quickly and easily create a light-weight snapshot of a view.

By calling the snapshotViewAfterScreenUpdates method, you have a snapshot of the main view. With the snapshot, we can add it to the container view to perform the animation. Note that the snapshot is added on top of the menu view.

For the actual animation when presenting the menu, the implementation is really simple. We just apply the moveDown transform to the snapshot of the main view and restore the menu view to its default position.

When dismissing the menu, the reverse happens. The snapshot of the main view slides up and returns to its default position. Additionally, the snapshot is removed from its super view so that we can bring the actual main view back.

Now open NewsTableViewController.swift and declare a variable for the MenuTransitionManager object:

In the prepareForSegue method, add a line of code to hook up the animation:

That’s it! You can now compile and run the project. Tap the menu button and you will have a slide down menu.

Detecting Tap Gesture

For now, the only way to dismiss the menu is to select a menu item. From a user’s perspective, tapping the snapshot should dismiss the menu too. However, the snapshot of the main view is non-responsive.

The snapshot is actually a UIView object. So we can create a UITapGestureRecognizer object and add it to the snapshot.

When instantiating a UITapGestureRecognizer object, we need to pass it the target object that is the recipient of action messages sent by the receiver, and the action method to be called. Obviously, you can hardcode a particular object as the target object to dismiss the view, but to keep our design flexible, we will define a protocol and let the delegate object implement it.

In MenuTransitionManager.swift, define the following protocol:

Here we define a MenuTransitionManagerDelegate protocol with a required method. The delegate should implement the dismiss method and provide the actual logic for dismissing the view.

In the MenuTransitionManager class, declare a delegate variable:

Later, the object which is responsible to handle the tap gesture should be set as the delegate object.

Lastly, we need to create a UITapGestureRecognizer object and add it to the snapshot. A good way to do this is define a didSet method within the snapshot variable. Change the snapshot declaration to the following:

Property observer is one of the powerful features in Swift. The observer (willSet/didSet) is called every time a property’s value is set. This provides us a convenient way to perform certain actions immediately before or after an assignment. The willSet method is called right before the value is stored, while the didSet method is called immediately after the assignment.

In the above code, we make use of the property observer to create a gesture recognizer and set it to the snapshot. So every time we assign the snapshot variable an object, it will immediately configure with a tap gesture recognizer.

We are almost done. Now go back to NewsTableViewController.swift, which is the class to implement the MenuTransitionManagerDelegate protocol.

First, change the class declaration to the following:

Next, implement the required method of the protocol:

Here, we simply dismiss the view controller by calling the dismissViewControllerAnimated method.

Lastly, insert a line of code in the prepareForSegue method of the NewsTableViewController class to set itself as the delegate object:

Great! You’re now ready to test the app again. Hit the Run button to try it out. You should be able to dismiss the menu by tapping the snapshot of the main view.

By applying custom view controller transitions properly, you can greatly improve the user experience and set your app apart from the crowd. The slide down menu is just an example, so try to create your own animation in your next app.

For reference, you can download the final project here.

Note: This tutorial is a sample chapter of our Intermediate iOS 8 Programming with Swift book.

Introducing SwiftUI TabView and Working with Tab Bar Customization
Using Gesture Recognizers to Handle Pinch, Rotate, Pan, Swipe and Tap Gestures
An Introduction to SpriteKit Part 2: Actions, Sequences and Gesture Recognizers
  • Chaos


    Author Reply

    the sample download in china is so slow ,only 10 kb in a sec.

  • Isuru Nanayakkara

    Very nice, short and easy to understand tutorial. Thank you.

  • Arif De Sousa

    Hello, I have a problem, if i present another ViewController when tapping one of the items in the Menu, when i go back I lose the bottom snapshot, is there a way to fix that? example, if i add “Settings” to Home, News, Tech, etc, and I present a Settings ViewController, when I dismiss It the bottom snapchat disappears.

    • Clockwork


      Author Reply

      You might have already found a solution, but you should unwind back to the ViewController before presenting the SettingsViewController. Then, dismissing the Settings should present the ViewController instead of the snapshot.

  • Khizar Nasir

    Hey Great Tutorial, But If you could, could you try out video tutorials, that would be great?

  • Bla Bla Bla

    Hi, what if I want to transition from bottom

  • Andres Felipe Guzman

    can i please have some help? i cannot give options a nil value…. is there any workaround? thanks!!

  • Andres Felipe Guzman

    Thanks for the tutorial i managed to change the options in the animation, but now i am trying the app out, and it is very slow when i select an item from the menu, this is what happens, i open the menu and deploy the animation, if i click right the way any item it works fine, but if i wait a couple of seconds ( which would be more likely in real life for a normal person ) the answer is too slow, i mean, i don’t see any change for like about 2 seconds. why is this? any idea?

    • Alberto Sigismondi

      for me too, have you found a solution?

      • Andres Felipe Guzman

        sorry for the late response! I had to load the view in a different way and use protocols :/ can`t remember exactly if you still need help let me know and i’ll check.

  • Antônio Coelho

    Hi , when you select a different “title” in the menu all it does is actually change the title of the view, how can I make it so when I click the title it also changes the entire view controller for example if I click “News” it goes to the news pages but when I click “Settings” it goes to a settings page??

    • Deyan Marinov

      Hi, have you found a solution?

    • Clockwork


      Author Reply

      You can try to use the performSegueWithIdentifier method from the UIViewController class.

  • Alex


    Author Reply

    Nice tutorial. But it works only inside a TabViewController or also in a ViewController?

  • Clockwork


    Author Reply

    There’s a small problem in this program : whenever you rotate, the app is quite messed up (it’s even worse when you play about with the menu).

    Otherwise, it’s a really nice transition.

  • Omkar Harmalkar

    Update it for Swift 3.0

  • aksel


    Author Reply

    need update to swift 3!

  • Kelvin Spencer