Apple Developer Support

It is great to see all the support that Apple Developers get in terms of tools, ecosystem, community and more.


For starters the Developer Support portal has a ton of information for the new comer as well as for the more expert of experts. Including guides and documentation for tools such as Xcode as well as information for developing software for MacOS and iOS.

Information about Design is available in the same place, including Human Interface Guidelines, Fonts (including downloads for San Francisco!) and information about accessibility and localisation.

Information about new tools and updates such as the latest about Swift, and SwiftUI can be easily found. And testing your apps with the help of tools such as TestFlight makes things so much easier.

Magic Mouse – Secondary Click Not Working

I have recently taken Mojave for a spin and I am really happy with the changes in the new OS. I know it is merely eye-candy, but I really like the dark theme. Things have been working well, but I came across a nagging issue with my MagicMouse:

For some reason the secondary click would simply not work. I had made sure the settings were enabled by making sure that the “Secondary Click” option was ticked (see screenshot below). I tried ticking it on and off, restarting the machine, deleting the mouse and reconnecting it… nothing had worked…

Finally I decided to take a look at some of the plist files and here is my solution to this problem:

    1. Go to the ~/Library/Preferences/ directory
    2. Delete the following files:
      Restart the machine

Et voilà!

Persistent “Previous Recipients” in Mac Mail

Hello everyone! I am very pleased to take a question from John who got in touch with Quantum Tunnel using the form here. John’s favourite scientist is Einstein and his question is as follows:

In Mac mail I cannot delete unwanted email addresses. I have done the routine of deleting all addresses from the previous receiptant list, but when starting a new email unwanted addresses appear.. Any help is appreciated. Thanks, John

John is referring to the solution I provided in this earlier post. Sadly, the list of his lucky friends/colleagues/family (delete as appropriate) he has email recently persists even after clearing the “Previous Recipients” as explained in the post before.

There may be a way to force the clearing of these persistent email address:

  • Quit Mail and Address Book (in case the latter is open)
  • Open a terminal and type the following command:
    • `rm ~/Library/Application Support/AddressBook/MailRecents-v4.abcdmr`
  • Log out and back in again
  • Start Mail
  • You may have to clear the “Previous Recipients” list as per the post mentioned above

You should now be able to clear the list. And… In case you were wondering, the file we deleted should be created afresh to start accumulating new “recent recipients” (yay!)

Et voilà!

CoreML – iOS Implementation for the Boston Model (part 2) – Filling the Picker

Right! Where were we? Yes, last time we put together a skeleton for the CoreML Boston Model application that will take two inputs (crime rate and number of rooms) and provide a prediction of the price of a Boston property (yes, based on somewhat all prices…). We are making use of three three labels, one picker and one button.

Let us start creating variables to hold the potential values for the input variables. We will do this in the ViewController by selecting this file from the left-hand side menu:








Inside the ViewController class definition enter the following variable assignments:

let crimeData = Array(stride(from: 0.1, through: 0.3, by: 0.01))
let roomData = Array(4...9)

These values are informed by the data exploration we carried out in an earlier post. We are going to use the arrays defined above to populate the values that will be shown in our picker. For this we need to define a data source for the picker and make sure that there are two components to choose values from.

Before we do any of that we need to connect the view from our storyboard to the code, in particular we need to create outlets for the picker and for the button. Select the Main.storyboard from the menu in the left-hand side. With the Main.storyboard in view, in the top right-hand corner of Xcode you will see a button with an icon that has two intersecting circles, click on that icon. you will now see the storyboard side-by-side with the code. While pressing the Control key, select the picker by clicking on it; without letting go drag into the code window (you will see an arrow appear as you drag):



You will se a dialogue window where you can now enter a name for the element in your Storyboard. In this case I am calling my picker inputPicker, as shown in the figure on the left. After pressing the “connect” button a new line of code appears and you will see a small circle on top of the code line number indicating that a connection with the Storyboard has been made. Do the same for the button and call it predictButton.



In order to make our life a little bit easier, we are going to bundle together the input values. At the bottom of the ViewController code write the following:

enum inputPredictor: Int {
    case crime = 0
    case rooms

We have define an object called inputPredictor that will hold the values of for crime and rooms. In turn we will use this object to populate the picker as follows: In the same ViewController file, after the class definition that is provided in the project by  default we are going to write an extension for the data source. Write the following code:

extension ViewController: UIPickerViewDataSource {

    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 2

    func pickerView(_ pickerView: UIPickerView,
                    numberOfRowsInComponent component: Int) -> Int {
        guard let inputVals = inputPredictor(rawValue: component) else {
            fatalError("No predictor for component")

        switch inputVals {
        case .crime:
            return crimeData.count
        case .rooms:
            return roomData.count

With the function numberOfComponents we are indicating that we want to have 2 components in this view. Notice that inside the pickerView function we are creating a constant inputVals defined by the values from inputPredictor.  So far we have indicated where the values for the picker come from, but we have not delegated the actions that can be taken with those values, namely displaying them and picking them (after all, this element is a picker!) so that we can use the values elsewhere. If you were to execute this app, you will see an empty picker…

OK, so what we need to do is create the UIPickerViewDelegate, and we do this by entering the following code right under the previous snippet:

extension ViewController: UIPickerViewDelegate {
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int,
                    forComponent component: Int) -> String? {
        guard let inputVals = inputPredictor(rawValue: component) else {
            fatalError("No predictor for component")

        switch inputVals {
        case .crime:
            return String(crimeData[row])
        case .rooms:
            return String(roomData[row])

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int,
                    inComponent component: Int) {
        guard let inputVals = inputPredictor(rawValue: component) else {
            fatalError("No predictor for component")

        switch inputVals {
        case .crime:
        case .rooms:


In the first function we are defining what values are supposed to be shown for the titleForRow in the picker, and we do this for each of the two elements we have, i.e. crime and rooms. In the second function we are defining what happens when we didSelectRow, in other words select the value that is being shown by each of the two elements in the picker. Not too bad, right?

Well, if you were to run this application you will still see no change in the picker… Why is that? The answer is that we need to let the application know what needs to be show when the elements load. Go back to the top of the code (around line 20 or so) below the code lines that defined the outlets for the picker and the button. There write the following code:

override func viewDidLoad() {
    // Picker data source and delegate
    inputPicker.dataSource = self
    inputPicker.delegate = self

OK, we can now run the application: On the top left-hand side of the Xcode window you will see a play button; clicking on it will launch the Simulator and you will be able to see your picker working. Go on, select a few values from each of the elements:

In the next post we will write code to activate the button to run a prediction using our CoreML model with the values selected from the picker and show the result to the user. Stay tuned!

You can look at the code (in development) in my github site here.

Core ML – What is it?

In a previous post I mentioned that I will be sharing some notes about my journey with doing data science and machine learning by Apple technology. This is the firsts of those posts and here I will go about what Core ML is…

Core ML is a computer framework. So what is a framework?  Well, in computer terms is a software abstraction that enables generic functionality to be modified as required by the user to transform it into software for specific purposes to enable the development of a system or even a humble project.

So Core ML is an Apple provided framework to speed apps that use trained machine learning models. Notice that word in bold – trained – is part of the description of the framework. This means that the model has to be developed externally with appropriate training data for the specific project in mind. For instance if you are interested in building a classifier that distinguishes cats from cars, then you need to train the model with lots of cat and car images.

As it stands Core ML supports a variety of machine learning models, from generalised linear models (GLMs for short) to neural nets. Furthermore it helps with the tests of adding the trained machine learning model to your application by automatically creating a custom programmatic interface that supplies an APU to your model. All this within the comfort of Xcode!

There is an important point to remember. The model has to be developed externally from Core ML, in other words you may want to use your favourite machine learning framework (that word again), computer language and environment to cover the different aspects of the data science workflow. You can read more in that in Chapter 3 of my “Data Science and Analytics with Python” book. So whether you use Scikit-learnm, Keras or Caffe, the model you develop has to be trained (tested and evaluated) beforehand. Once you are ready, then Core ML will support you in bringing it to the masses via your app.

As mentioned in the Core ML documentation:

Core ML is optimized for on-device performance, which minimizes memory footprint and power consumption. Running strictly on the device ensures the privacy of user data and guarantees that your app remains functional and responsive when a network connection is unavailable.

OK, so in the next few posts we will be using Python and coreml tools to generate a so-called .mlmodel file that Xcode can use and deploy. Stay tuned!

Machine Learning with Apple – An Open Notebook

We all know how cool machine learning, predictive analytics and data science concepts and problems are. There are a number of really interesting technologies and frameworks to use and choose from. I have been a Python and R user for some time now and they seem to be pretty good for a lot of the things I have to do on a day-to-day basis.

As many of you know, I am also a mac user and have been for quite a lot time. I remember using early versions of Mathematica on PowerMacs back at Uni… I digress..


Apple has also been moving into the machine learning arena and has made available a few interesting goodies that help people like me make the most of the models we develop.

I am starting a series of posts that I hope can be seen as an “open notebook” of my experimentation and learning with Apple technology. One that comes to mind is CoreML, a new framework that makes running various machine learning and statistical models on macOS and iOS natively supported. The idea is that the framework helps data scientists and developers bridge the gap between them by integrating trained models into our apps. Sounds cool, don’t you think? Ready… Let’s go!

Jupyter not Launching after Updating to MacOS 10.12.5

If you have been itching to update the operating system on your shiny Mac, beware that there is a broken link when launching Jupyter.

Do not panic, simply follow these simple steps:

  • Open a terminal and type the following command:
jupyter notebook --generate-config
  • In the terminal navigate to the place where the configuration file is. In other words, type the following:
cd ~/.jupyter/
  • Open the file and look for a line that says:
# c.NotebookApp.browser = ''

Change the line as follows: Delete the hash and write the name of your browser in between the quotes.

For SAFARI it would look as follows

c.NotebookApp.browser = 'safari'

If you are a CHROME supporter, the command looks a tad bit more complicated:

c.NotebookApp.browser = 'open -a /Applications/Google\ %s'
  • Save the script and close it.
  • Restart your terminal and launch Jupyter…

Et voilà!

Installing Spark 1.6.1 on a Mac with Scala 2.11

I have recently gone through the process of installing Spark in my mac for testing and development purposes. I also wanted to make sure I could use the installation not only with Scala, but also with PySpark through a Jupyter notebook.

If you are interested in doing the same, here are the steps I followed. First of all, here are the packages you will need:

  • Python 2.7 or higher
  • Java SE Development Kit
  • Scala and Scala Build Tool
  • Spark 1.6.1 (at the time of writing)
  • Jupyter Notebook


You can chose the best python distribution that suits your needs. I find Anaconda to be fine for my purposes. You can obtain a graphical installer from I am using Python 2.7 at the time of writing.

Java SE Development Kit

You will need to download Oracle Java SE Development Kit 7 or 8 at Oracle JDK downloads page. In my case, at the time of writing I am using 1.7.0_80. You can check the version you have by opening a terminal and typing

java -version

You also have to make sure that the appropriate environment variable is set up. In your


  add the following lines:

export JAVA_HOME=$(/usr/libexec/java_home)

Scala and Scala Build Tool

In this case, I found it much easier to use Homebrew to install and manage the Scala language. I f you have never used Homebrew, I recommend that you take a look. To install it you have to type the following in your terminal:

ruby -e "$(curl -fsSL"

Once you have Hombrew you can install Scala and the Scala Build Tool as follows:

> brew install scala
> brew install bst

You may want to create appropriate environments in your 



export SCALA_HOME=/usr/local/bin/scala

Spark 1.6.1

Obtain Spark from

Note that for building Spark with Scala 2.11 you will need to download the Spark source code and build it appropriately.


Once you have downloaded the tgz file, unzip it into an appropriate location (your home directory for example) and navigate to the unzipped folder (for example



To build Spark with Scala 2.11 you need to type the following commands:

> ./dev/
> build/sbt clean assembly

This may take a while, so sit tight! When finished, you can check that everything is working by launching either the Scala shell:

> ./bin/spark-shell

or the Python shell:

> ./bin/pyspark

Once again there are some environment variables that are recommended:

export SPARK_PATH=~/spark-1.6.1
export PYSPARK_DRIVER_PYTHON="jupyter" 
alias sparknb='$SPARK_PATH/bin/pyspark --master local[2]'

The last line is an alias that will enable us to launch a Jupyter notebook with PySpark. Totally optional!

Jupyter Notebook

If all is working well you are ready to go. Source your


  and  launch a Jupyter notebook:

> sparknb

Et voilà!

Google Drive not synching on your Mac? Here is what to do

I am not a big used of Google Drive. It is a good service and it mostly does what one may need from a suite of productivity apps… but for some reason I only use it in very limited cases.

So, no surprise that I had not noticed that the synching between the cloud version of my documents and those in my mac had gone pear shaped. I tried logging out of Drive but that did not help. I attempted forcing the synch by making changed in both the cloud version and the Mac, but same result. Google Drive

I managed to sort it out in the end and here is what I did:

  1. Exit the Drive application
  2. Navigate to the Application Support folder and look for the Google folderYou may need to find the hidden Library folder
    • In Finder look for the Go menu and press Option + Cmd to reveal the hidden folder
    • Once there look for the “Application Support”
    • Alternatively you can press Cmd + Shift + G and go to “~/Library/Application Support/Google”
  3. Delete the Drive fokder
  4. Start the Drive application

Et voilà