Announcing Clockwise App

The past few weeks I have been working on a iOS application for kids to learn to read the clock. So today, I’m really excited to announce that Clockwise – Learn to read the clock is available in the App Store!

I already had the idea for a while to create an educational app for my 3 kids, but because of the Covid19 pandemic, I finally decided to have a go at it.

The game has been made in Swift 5.2 & Apple’s SpriteKit framework. The books of Paul Hudson ( were really helpful as I did not have any experience a few months ago with SpriteKit.

Go ahead, download Clockwise, and let me know what you think!

Streamlining lots of View Controller interactions with Swift enums.

What ‘problem’ am I trying to solve?

In most cases a View Controller shows one screen to a user, but the user can interact with the screen in multiple ways. Every one of these interactions is handled differently in code. This can be through delegation, target-action, notifications, callbacks, …

For example, take the Travelplanner screen of the Reisplanner Extra app I’m working on.

Overview actions on TravelPlanner screen

  1. A modal Location Picker is presented when the row is pressed
  2. From & To locations are switched when pressed
  3. A modal Location Picker is presented when the row is pressed
  4. A modal Date Picker is presented when the row is pressed
  5. The Now toggle button can be in an on/off/automatic state and changes the behavior of the time row
  6. A modal Travel Options screen is presented when the button is pressed
  7. 8. 9. 10. … more actions 🙂

As you can see, there are a lot of interactions (and there are actually even more interactions for different states of this screen), and all of these interactions need to be handled in code.

In most cases you’ll end up with all kinds of different methods handling these cases, but over time it can start to become unclear where to look when something needs to be changed or added inside your View Controller.

When a (new) team member has to work in the codebase that he has never touched before, it can take some time to find his/her way and know where to look. So how do I try to streamline this?

Swift Enums, your best friend.

Every interaction on the screen, triggers something, and I model all these interactions in a Swift enum called PerformAction .

The enum for the TravelPlanner screen looks like this:

enum PerformAction {
    case fromLocationRowPressed( location:Location? )
    case toLocationRowPressed( location:Location? )
    case switchLocationButtonPressed
    case departureArrivalRowPressed( queryType:TravelTimeQueryType, date:Date )
    case nowButtonPressed
    case travelOptionsButtonPressed
    case widgetDirectTo_optionsButtonPressed
    case widgetDirectTo_configureAddressButtonPressed
    case widgetDirectTo_selectLocation( location:Location )
    case widgetCiCo_optionsButtonPressed
    case nothing


This enum is added as a nested type inside the TravelPlannerViewController, so you can reuse the same PerformAction enum name across your files without getting name collisions.

class TravelPlanneViewController: UIViewController {

    enum PerformAction { ... }

If a new member starts reading through your codebase, he/she can check this enum and see at a glance what all the different actions are for this screen.

To react on these interactions, we create a property performedActionand add a didSet property observer.

var actionPerformed:PerformAction = .nothing {

    didSet {
        switch actionPerformed {
        case .fromLocationRowPressed( let location ):
            presentLocationPicker( location: location )
        case .toLocationRowPressed( let location ):
            presentLocationPicker( location: location )
        case .switchLocationButtonPressed:
        case .departureArrivalRowPressed( let queryType, let date ):
            presentDatePicker( queryType, date: date )



Now you have 1 point of entry to handle all your interactions and call your methods.

@IBAction func fromLocationPressed( _ sender: UIButton ) {
  actionPerformed = .fromLocationRowPressed( location: fromLocationRow.location )

@IBAction func switchButtonPressed( _ sender: UIButton ) {
  actionPerformed = .switchLocationButtonPressed

When using RxSwift I use a PublishSubject to keep track of changes.

// Create the subject to keep track of the performed actions
private let performedActionSubject = PublishSubject<PerformedAction>()
// Add a new action to the stream
performActionSubject.onNext( .travelOptionsButtonPressed )
// Get updates when an action has been performed
viewModel.outputs.actionPerformedObservable.subscribe(onNext: { [weak self] (performedAction) in
    switch performedAction {
        case ...

}).disposed( by: disposeBag )

Final thoughts

This is not a technique I use for a screen with only one or two actions. I tend to model it like this, if there are a lot of interactions.

The downside is you’ll get a bit of extra code, because you proxy your interaction handling to the PerformAction enum.

The benefits are

  1. See all the interactions in the enum at a glance
  2. Clarity of having one point where all the interactions are handled

For newcomers (or your future-you) it will be easier to get around the code.

If you enjoyed this post, follow me on Twitter @thenerd_be 

Swift Snippet : Map Bool values with Generics in Swift

My problem

It often occurs while writing code that you need to assign a value of a certain type, based on the value of Boolean. To do this there are multiple ways, but the 2 most known are

1. The let’s-write-a-lot-of-code approach

let isAWildBoolean = true

// Set the value of `offSet` to a value based on the Boolean
let offSet:Int

if isAWildBoolean {
    offSet = 10
} else {
    offSet = 20

I don’t like the first approach, because it creates a bloated codebase. A better way is to use the ternary operator (also known as the inline-if).

2. The one-line-star-developer (ternary operator) approach

You specify the Boolean you want to evaluate, add a question mark, followed by the value if the Boolean is true, followed by a colon, followed by the value if the Boolean is false.

Continue reading Swift Snippet : Map Bool values with Generics in Swift

Integrate Unity 5 in a native iOS app with Xcode 7

Integrate Unity 5 in a native iOS app

A few months back I published a blog post about how to integrate Unity3D within a native iOS application.  This tutorial was written for Xcode 6 & Unity 4 and in the comments there were a lot of requests for a new tutorial.

Tonight I found the time to make the video tutorial on how to integrate Unity 5 in a native iOS app with Xcode 7, so I hope you enjoy it!

Continue reading Integrate Unity 5 in a native iOS app with Xcode 7

3D touch peek and pop tutorial for your Swift application

3D Touch peek and pop tutorial

Apple added a touch-sensitive layer to the screen of the brand new iPhone 6s (plus).  With the coming of this new screen, they’ve added some new UI interactions like application shortcuts and peek and pop.

In this 3D touch peek and pop tutorial I will learn you how to implement this new way of interacting with your content by building a photo gallery.  When you press hard on the screen you’ll see a preview of the image and if you press really hard the preview will pop into a detail view.

At the end of this tutorial I’ll show you how to add preview actions. This way you can interact with the content without going to the detail view.  You can do this by swiping up while you are previewing the content.

Continue reading 3D touch peek and pop tutorial for your Swift application

Add 3D Touch quick actions tutorial

3d touch quick actions tutorial

With the introduction of the iPhone 6S (plus), Apple added a pressure-sensitive layer to their screen.  This creates a bunch of new UX possibilities for creating apps.  It’s possible to do a hard press on an application icon and get shortcuts which take you to a specific point in your app.  For example, if you do a hard-press on the Photo’s app icon you can quickly search for an image, check the most recent images or see your favourites.  It’s also possible to make these quick actions dynamic, meaning that you can add and remove actions based on the state of your application.

3D touch quick actions
3D touch quick actions

In this tutorial I will show you how you can add these quick actions to your application icon.

Continue reading Add 3D Touch quick actions tutorial

A better way to integrate Unity3D within a native iOS app

Update: I’ve created a new tutorial for Xcode 7 & Unity 5.

Last year I published a blog post about how to integrate Unity3D within a native iOS application.

Last week I found a better way to integrate Unity3D within a native iOS app, which also eliminates some issues with my previous version.  Because it’s quite a long explanation to do and I noticed in my previous blog post that not everything was crystal clear, I’ve made a video tutorial how you can achieve this.

Continue reading A better way to integrate Unity3D within a native iOS app

Custom cells for UIPickerView with AutoLayout

For a project I needed to add a UIPickerView with custom cells using AutoLayout.  UIKit allows this via the UIPickerViewDelegate method pickerView(_:viewForRow:forComponent:reusingView).

The cell just needed an UIImageView and UILabel, so I thought it would be pretty straightforward to do, but there are some caveats you need to know. Big thanks to Tom Adriaenssen for pointing them out and not ruining my Sunday afternoon 🙂

Continue reading Custom cells for UIPickerView with AutoLayout

TNImageSliderViewController – an image slider gallery for Swift

The problem

Too many times a client has asked to add a sliding image gallery to an iOS app, so I wrapped it up in a little component. You can download it from GitHub.

Introducing an image slider gallery for Swift

I took some time to write this component, so it is easy to manage image slider galleries.  First I looked around on the web, but there was nothing that really fitted my needs, so the best thing to do in such a case is write it yourself :-).


  • Xcode
  • iOS8+


  • Horizontal scrolling
  • Vertical scrolling
  • Page control to indicate how many photos are in the list
  • Works in both orientations (landscape, portrait)
  • Cell reuse (works on UICollectionVIew)


You can download the project on GitHub.  If you have any questions, just ask it on  Twitter, put a comment below or open an issue on GitHub.

The component is also available via CocoaPods.