ChristianRendezvous.com

Hi everybody!

I have bought the domain christianrendezvous.com and christianrdv.com. I am going to build a platform for christian people so that they can communicate and exchange information. If you want to join me for this project, let me know.

See you

Phil

Rename multiple files

When we want to rename a file (with Linux or Mac OS), we  generally go to the directory of the file and we rename the file. Or for those who prefer doing with the terminal, we use mv

And how about multiple file ? How about renaming all episode of Game of Throne ?

• How can we remove [TOTO] for every file name ?
• How can we rename secretFile for every file name ?
• How can we remove the extension for every file name ?
• How can we upper case every file name ?
• and so on …

we generally do

• one by one
• or a bash script

or

To rename multiple files, we will use rename. But what’s rename ?

Rename is a program that renames files according to modification rules specified on the command line.

Install rename program

To install rename, we will use homebrew (a package manager for OSX. With homebrew we can install a lot of applications and libraries that would require manual compilation)

1. open the terminal
2. enter “brew install rename”
3. done

Or use Cakebrew (The Mac App for Homebrew)

Now let’s rename:

Append the string argument you supply to every filename: rename -a ‘ toto’ *
(-a: append the string argument you supply to every filename)

Prepend the string argument you supply to every filename: rename -A ‘ toto’ *
(-A: prepend the string argument you supply to every filename)

Convert file names to all lower case: rename -c -f *
(-c: convert file names to all lower case)
(-f: rename even when a file with the destination name already exists)

Convert file names to all upper case: rename -C -f *
(-c: convert file names to all upper case)

Remove the last extension from a filename, if there is any: rename -x *

Replace all sequences of whitespace in the filename with single underscore characters: rename –nows *

Replace each underscore in the filename with a space: rename –rews *

Perform a simple textual substitution of “from” to “to”:
rename -s ‘want to change’ ‘to what we want’ *

Add increment number for each file in the list from 1: rename -N …01 -X -e ‘$_ = “$_-$N”‘ *
(-X  stand for keep the extension)
(-e stand for expression)
($_ is the name of the file in the expression)
($N is the incrementation number in the expression)

Add increment number for each file in the list from 3: rename -N …03 -X -e ‘$_ = “$_-$N”‘ *

Throw away all the existing filenames and simply number the files from 1: rename -N …01 -X -e ‘$_ = “FileName-$N”‘ *

That was only the surface of the iceberg. To see other parameter use:

man rename 

Cool isn’t it ?
So let rename it !

IOS APP PROGRAMMATICALLY: UILabel, UITextField and UIButton

In this tutorial, we will add some basic elements to our view. We will use :

1. UILabel
2. UITextfield
3. UIButton

At the end, you will be able to change :

1. change the background colour of the view
2. add labels to view, change font, size, alignment and colour
3. add textfield to the view (similar to login and password field)
4. add button to the view, change button layout and add event on click button

For this tutorial, we use:

1. Xcode 8.2
2. Swift 3

Previous Tutorial:

• iOS App Programmatically: Working without the storyboard

UILabel

UILabel it’s a view that display read-only text (i.e: title, description, label, …). More information in Apple API Reference.

At the end of this section, we will have something like this :

We will use the same project that you can find on the previous tutorial.

Let’s start !

1. select ViewController.swift on the project navigation.
   
2. remove comment in viewDidLoad and remove the function didReceiveMemoryWarning. We will do all programming logic in viewDidLoad. We will explain in another article the life cycle of the ViewController. For now, we didn’t need. However you can find information in Apple API Reference UIControllerView.
3. change the colour background by adding in viewDidLoad:

   • let blueColor = UIColor(red: 0.0/255.0, green: 118.0/255.0, blue: 255.0/255.0, alpha: 1.0)

   • self.view.backgroundColor = blueColor

   • you can also use other default colour: self.view.backgroundColor = UIColor.red
     
4. create a property for the label before the function viewDidLoad(). Note: UILabel is import within UIKit (UIKit.UILabel).

   • let label = UILabel()

   • 
5. add text to the label and customise it 
   • add text to the label
     

     self.label.text = “My first UILabel !”

   • change color text label
     

     self.label.textColor = UIColor.white

   • text alignment to center
     

     self.label.textAlignment = .center

   • change font to bold and change size to 20
     

     self.label.font = UIFont(name: “HelveticaNeue-Bold”, size: 20)

   • you can have more property by pressing cmd + click on the UILabel
6. then add the label to the view
   • !!! we will add manually the constraint so we have to put autoresizingMaskIntoConstraints to false !!!
     

     self.label.translatesAutoresizingMaskIntoConstraints = false

   • add label to the view
     

     self.view.addSubview(self.label)

7. the label didn’t show yet, we have to add where to display on the view. So for now, we will just put in the center of the view by adding some constraints. (we will explain constraints in another tutorial)
   • keep constraints in variable
     

     var constraints = [NSLayoutConstraint]()

   • center label from horizontal view
     

     constraints.append(NSLayoutConstraint(item: self.label, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerX, multiplier: 1.0, constant: 0.0))

   • center label from vertical view
     

     constraints.append(NSLayoutConstraint(item: self.label, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerY, multiplier: 1.0, constant: 0.0))

   • active constraints
     

     NSLayoutConstraint.activate(constraints)

8. we have done. Here is the result and codes.
   

UITextField

UITextField it’s a view that display an editable text area (i.e: login, password, email, …). More information in Apple API Reference UITextField.

At the end of this section, we will have something like this :

For this section of tutorial, you can use the empty project that you can find on the previous tutorial and do the point 1 & 2 of the previous section (UILabel). Or you can continue what was done in the previous section (UILabel). Just hide the label by adding

self.label.isHidden = true

Let’s start !

1. create a property for the textfield before the function viewDidLoad(). Note: UITextField is import within UIKit (UITextField).

   • let textfield = UITextField()

2. add more information in the textfield
   • background text in the textfield
     

     self.textfield.placeholder = “information text”

   • if it’s a password field or sensitive field, add isSecureTextEntry = true otherwise it is false by default
     

     self.textfield.isSecureTextEntry = false

   • change the enter text colour to blue
     

     self.textfield.textColor = UIColor.blue

   • change the enter text alignment to center
     

     self.textfield.textAlignment = .center

   • change the background field to white
     

     self.textfield.backgroundColor = UIColor.white

   • change the border to line
     

     self.textfield.borderStyle = .line

   • we remove the autocorrectionType (important when using for sensitive field as login and password)
     

     self.textfield.autocorrectionType = .no

   • display the clean field when we have something in the textfield
     

     self.textfield.clearButtonMode = .whileEditing

   • you can have more property by pressing cmd + click on the UITextField
3. then add the textfield to the view
   • !!! we will add manually the constraint so we have to put autoresizingMaskIntoConstraints to false !!!
     

     self.textfield.translatesAutoresizingMaskIntoConstraints = false

   • add textfield to the view
     

     self.view.addSubview(self.textfield)

4. add constraints [center to the screen with width=150 and high=50]
   (we will explain constraints in another tutorial)
   • keep constraints in variable (if not create yet)
     

     var constraints = [NSLayoutConstraint]()

   • variable metrics and views for width and high constraint
     

     let views = [“textfield”: self.textfield]
     let metrics = [“width150”: 150, “high50”: 50]

   • center textfield from horizontal view
     

     constraints.append(NSLayoutConstraint(item: self.textfield, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerX, multiplier: 1.0, constant: 0.0))

   • center textfield from vertical view
     

     constraints.append(NSLayoutConstraint(item: self.textfield, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerY, multiplier: 1.0, constant: 0.0))

   • width of the textfield
     

     constraints += NSLayoutConstraint.constraints(withVisualFormat: “H:[textfield(width150)]”, options: [], metrics: metrics, views: views)

   • high of the textfield
     

     constraints += NSLayoutConstraint.constraints(withVisualFormat: “V:[textfield(high50)]”, options: [], metrics: metrics, views: views)

   • active constraints
     

     NSLayoutConstraint.activate(constraints)

5. we have done. Here is the complete code.
   

UIButton

UIButton it’s a view that executes your custom code in response to user interactions. More information in Apple API Reference UIButton.

At the end of this section, we will have something like this :

For this section of tutorial, you can use the empty project that you can find on the previous tutorial and do the point 1 & 2 of the previous section (UILabel). Or you can continue what was done in the previous section (UITextField). Just hide the textfield by adding

self.textfield.isHidden = true

Let’s start !

1. create a property for the button before the function viewDidLoad(). Note: UIButton is import within UIKit (UIKit.UIButton).

   • let button = UIButton()

2. add information for the button and customise it
   • button text
     

     self.button.setTitle(“confirm”, for: .normal)

   • change the colour of the text button (ie.: if you want to modify the text colour of the button when highlight, just add self.button.setTitleColor(UIColor.red, for: .highlight) )
     

     self.button.setTitleColor(UIColor.blue, for: .normal)

   • change the background of the button
     

     self.button.backgroundColor = UIColor.orange

   • we put the border edge colour of the button to black
     

     self.button.layer.borderColor = UIColor.black.cgColor

   • change the border size to 2
     

     self.button.layer.borderWidth = 2

   • round the corner of the button
     

     self.button.layer.cornerRadius = 3

   • you can have more property by pressing cmd + right click on the UIButton
3. then add the button to the view
   • !!! we will add manually the constraint so we have to put autoresizingMaskIntoConstraints to false !!!
     

     self.button.translatesAutoresizingMaskIntoConstraints = false

   • add button to the view
     

     self.view.addSubview(self.button)

4. add constraints [center to the screen with width=150 and high=50]
   (we will explain constraints in another tutorial)
   • keep constraints in variable (if not create yet)
     

     var constraints = [NSLayoutConstraint]()

   • variable metrics and views for width and high constraint
     

     let views = [“button”: self.button]
     let metrics = [“width150”: 150, “high50”: 50]

   • center button from horizontal view
     

     constraints.append(NSLayoutConstraint(item: self.button, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerX, multiplier: 1.0, constant: 0.0))

   • center button from vertical view
     

     constraints.append(NSLayoutConstraint(item: self.button, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerY, multiplier: 1.0, constant: 0.0))

   • width of the button
     

     constraints += NSLayoutConstraint.constraints(withVisualFormat: “H:[button(width150)]”, options: [], metrics: metrics, views: views)

   • high of the button
     

     constraints += NSLayoutConstraint.constraints(withVisualFormat: “V:[button(high50)]”, options: [], metrics: metrics, views: views)

   • active constraints
     

     NSLayoutConstraint.activate(constraints)

5. we have done. Here is the complete code.
   

Put all together (UILabel, UITextField, UIButton)

So now, we know how to add and display UILabel, UITextField and UIButton. We have all elements to do the interface :

• UILabel that display What’s your name ?
• UITextfield where we can add a name
• UIButton to confirm the name

What we need to do :

1. we need to add a second label to display the name after clicking on the button (try to do it yourself)
2. add constraints to organise elements on the view
3. add action on click button

 

 

1. we need to add a second label to display the name after clicking on the button

here is the code to the second label 🙂

2. add constraints to organise elements on the view

So now, we just need to play with the constraint to display as we want. (we will explain constraints in another tutorial). Here is the code:

Now if we launch the application, the display is as we want. However the button is not active. Nothing happen when we click on the button and the button doesn’t change colour for informing of the touch.

So let’s do it.

3. add action on click button

When we click on the button, we want to display our second label with the text “Your name is Toto”

1. create a function with the wanted action (outside of the viewDidLoad function)
   

   func buttonAction(sender: UIButton) {
   self.label2.text = self.textfield.text
   }

   func : declaration of the function
   sender: UIButton : reference of the button that use this function
   self.label2.text = self.textfield.text : get the text of the textfield and copy to the label2 text

   here we will display only the name. we want to add “Your name is …”

   func buttonAction(sender: UIButton) {
   guard let name = self.textfield.text else {
   self.label2.text = “”
   }
   self.label2.text = “Your name is ” + name
   }

   We use a guard let because self.textfield.text is optional. Another way to do this:

   func buttonAction(sender: UIButton) {
   let name = self.textfield.text else {
   self.label2.text = “”
   return
   }
   self.label2.text = “Your name is ” + name
   }

   • 
2. bind the function with the button
   

   self.button.addTarget(self, action: #selector(self.buttonAction), for: .touchUpInside)

So now when we click on the button, it will show above the button confirm : “Your name is …”

4. Change colour of the button for informing of the touch

to change background color while highlighted we have 3 ways to this:

1. the easiest is by adding target
   • create function to change button background colour
     
   • add target
     
2. use extension UIButton -> see UIButton+extension.swift
   • create a new class (call it UIButton+extension.swift)
     
   • implement the class
     
   • use new property for the button
     
3. use property observer with highlighted property
   • create a new class (call it UIButton+inheritace.swift)
     
   • implement the class
     
   • create the button with the new class
     

 

CONGRATULATION

You have create your first application programmatically.

You can download the tutorial project:
https://github.com/ndtran/ToMyLab/tree/master/Tutorial2

NEXT STEP

The next step will be to understand NSConstraint and UIViewController

How to install your Raspberry Pi OS (Raspbian) in 4 minutes

This tutorial will take you through the steps to install Raspbian, the official OS optimized for Raspberry Pi.

Prerequisites

• Rapsberry Pi (any model)
• SD card (for Pi version 1), or micro SD card (for Pi version 2 & 3)
• SD Card reader (for your Mac/PC from which you will format the SD card)
• A Mac / PC / Linux computer.

Download, unzip and burn the image

Download the Raspbian image

Raspbian is declined in two version. Raspbian Jessie Lite comes as a minimal image based on Debian Jessie without graphical environment. So it is a light version (~308.5MB) and it is a good candidate if you intend to install a server. (Direct download to Raspbian Jessie Lite)
The second variant is Raspbian Jessie with PIXEL. Much heavier (~1.57GB) but comes with some extra features such as X-server and its component. (Direct download to Raspbian Jessie with PIXEL)

Note that, at any time, you can install a desired package with apt-get, and go from the minimal image to the full Raspbian Jessie with Pixel if needed.
PIXEL is not a name but an acronym. It stands for Pi Improved Xwindows Environment, Lightweight, which makes fully sense in that context.

Unzip the image

On Linux, Unix and MacOS platform there is no problem to unzip the image. But if you have a Windows operating system, the specialized forums recommend you to use 7zip to decompress the file.

For this tutorial, I will uncompress the Raspbian Jessie Lite variant and will get:

Alternative way (for BSD or macOS): you can unzip and burn the image in one statement:

unzip -p 2017-03-02-raspbian-jessie-lite | dd of=/dev/sdb bs=1M

Time to use strong acid to cut the metal!

Etcher (meaning) is a fantastic tool (developed with electron) to easily burn images to SD cards & USB drives. You can download it from here: link

After the installation, select the image, connect the drive (SD card), and burn it. It’s easy and simple.

!! Do not forget to safely eject your SD card !!

When it’s done, you are welcome to plug into your RPi and enjoy your newly born OS.

Alternative tool: I can also recommend you UNetbootin to burn images to USB drives or SD cards. 

 

iOS App Programmatically: Working without the storyboard

You want to start a new iOS project without using the storyboard or nib ? This tutorial is for you.

In this tutorial, we will:

1. Create new project
2. Remove the storyboard
3. Setup the AppDelegate.swift

For this tutorial, we use:

1. Xcode 8.2
2. Swift 3

Next tutorial:

• iOS App programmatically: UILabel, UITextField and UIButton

Create new project

The first step, select “create a new Xcode project”

Then select “Single View Application”

Next, fill the textfields with your informations.

•  Product Name: the name of your application
• Organization Name: the name of your organization
• Organization Identifier: generally, you inverse your website url name
• Language: we will use “swift”
• Devices: select iPhone or iPad or Universal (for iPhone and iPad)
• In this tutorial, we will not use Core Data (iOS database)

Finally, save the project to your computer. If you use Git, check “Create Git repository” or you can also do it manually later.

The project navigator should look like this

Remove the storyboard

After creating the project, we will remove the storyboard from the project. So in the project navigator, delete “Main.storyboard” 

Then select “Move to Trash” on the alert window

Next, select “info.plist” in the project navigator and you will find “Main storyboard file base name”. Delete it.

We have now remove the storyboard from the project. You can launch the application however the application will be empty (black screen).

Set up the AppDelegate

The AppDelegate is the root object of your application. It has several important roles.

• It contains your app’s startup code.
• It responds to key changes in the state of your app.
• More information here.

In the “didFinishLaunchingWithOptions” add the following line:

self.window = UIWindow(frame: UIScreen.main.bounds)

It will initialise the window with the size of the screen device.

guard let window = self.window else { fatalError(“no window”) }

A guard let to be sure that the window is not nil.

window.rootViewController = ViewController()

Set the root view controller of the app’s window.
ViewController() : instance of the ‘ViewController’ class which is locate in the project navigator. For less confusion, you can rename the class and the file name by MainViewController or MainVC.

window.makeKeyAndVisible()

Make the window visible.

The AppDelegate should be similar to this:

You can download the tutorial project:
https://github.com/ndtran/ToMyLab/tree/master/Tutorial1/

Next step

Now you have setup your project and you can start to modify the view programmatically. The next step will be to add some elements as UILabel, UIButton or UITextField, to the user interface.

Next tutorial: iOS App programmatically: UILabel, UITextField and UIButton

Forget about Bash Shell, Zsh+Oh-My-Zsh is sexier!

For any developer, the terminal is THE most important daily tool. And Even if Bash and Zsh are both excellent Shells, we all have our preferences.

In my opinion, a product itself is nothing comparing to an ecosystem or a community. And this is why I love Zsh: this tool is great for my needs.

Four reasons to use Zsh over Bash:

1. Autocorrection – try to type gir -m ‘my commit message’ in a Bash or in a Zsh to see the autocorrection in action.
2. If you are on MacOS, your bash is old! Type a bash –version in your terminal to compare with the actual stable version 4.4.5
3. Command completion – git and cd command completion are more powerful on Zsh than Bash.
4. The greatest of the path replacement

Enough talk, let’s cut to the chase!

Prerequisites:

• Internet connection
• Homebrew
• Admin rights

Install Zsh and Zsh-Completions

To check if you already have a version, type:

which zsh

I have already a version of Zsh on my MacOS but it isn’t the newest. So I decide to update this system-provided version using Homebrew and Zsh-Completions

brew install zsh zsh-completions

Change the default Shell to Zsh

To add or change the user database information and in particulary change the user shell, type this command:

chsh -s /usr/local/bin/zsh

Install Oh-My-Zsh

Now it’s time to get additional functionality with Oh-My-Zsh framework on top of Zsh. To do this, you will need to go back to your home directory and install Oh-My-Zsh:

cd ~
curl -L https://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh | sh

After a restart to load the Zsh shell, you can already notice the change:

[Optionally] Apply another theme and configure your .zshrc

Open the .zshrc file with your favorite text editor, for example

vim ~/.zshrc

and apply for example the theme ‘agnoster‘: at the line 9 (in my version), change it with:

ZSH_THEME="agnoster"

save it.

Go to Powerline-Fonts, download it, unzipped, and install it:

unzip~/Downloads/fonts-master.zip 
./fonts-master/install.sh 

To have some eye friendly colour combinations, we have to install Solarized Light and Solarized Dark themes. Go to ethanschoonover.com/solarized, under the Download section get the lastest .zip file. Then:

unzip ~/Downloads/solarized

Go under Downloads/solarized/osx-terminal.app-colors-solarized/ and with the ‘alt’ key pressed (to bypass the macOS defenses) click on the Solarized Dark ansi.terminal and Solarized Light ansi.terminal

In the terminal preferences (Settings -> Profiles), click on Solarized Dark and then the Default button.

Finally, you should see your terminal ending like:

[Optionally] Add some plugins to your Oh-My-Zsh

You also can add some plugins to simplify your daily life. In my .zshrc file, I have replaced plugins=(git) with the following:

plugins=(git colored-man colorize github brew osx zsh-syntax-highlighting sublime xcode)

Reference

https://github.com/robbyrussell/oh-my-zsh

http://ohmyz.sh/

github.com/powerline/fonts

My first steps in iOS dev world

This app tracks facial features, use an animation with visual effects and I have considered functionality, performance and creativity/novelty.

Youtube video

Link: github repository