Articles & News from Kt. Academy

Hello, Kt. Academy here 👋

In today’s newsletter you’ll find:
➡️ New article published on our blog!
➡️ Article private comment function.
➡️ New articles for our polish audience.
➡️ Places to buy the Effective Kotlin book.

Enjoy!

Data modifier is a powerful tool 💪
If you want to learn how it works as well as what are its perils and dangers, read the article written by Marcin Moskala 👇
Use the data modifier to represent a bundle of data.

We want our audience to have an impact on what we publish and so that you can share your thoughts or concerns, and be able to leave us any other feedback about our articles!

That’s why we’ve added the article private comment function to our blog 🥳

To leave us your comments click on a small chat icon on the right side 💬, write what you think and send it straight to us — exactly as shown in the video below 👇

To our Polish audience 🇵🇱

There are 2 new articles about JavaScript on our polish blog:
👉 Tablice w JavaScript
👉 Iteracja po tablicy w JavaScript

As always, you can leave us your comments or become our reviewer directly from the article page.

❗️Here’s a quick reminder that the Effective Kotlin book is still on sale❗️

✅ paper book available worldwide on Amazon
✅ ebook available on Amazon Kindle and LeanPub
✅ the polish versions — in paper and ebook — available on Helion 👉 now on sale! 🤩

Thanks and see you soon!

Kt. Academy Team

www: kt.academy
Blog: blog.kotlin-academy.com
Twitter EN: @KtDotAcademy
Twitter PL: @ktdotacademyPL
FB: @KtDotAcademy
LinkedIn: @Kt. Academy


Articles & News from Kt. Academy was originally published in Kt. Academy on Medium, where people are continuing the conversation by highlighting and responding to this story.

Continue ReadingArticles & News from Kt. Academy

New tools on our website

We are constantly working to improve our website to make it easier to use. That’s why we recently added some extra tools that will make your experience better and more intuitive.

Online course functionality — we’ve created this tool to share open courses and to leave our workshop participants with follow-up materials. All the workshop attendees now have online access to the videos and exercises from the course (plus some extra), resources, and suggestions on what to learn next. All others can make our preparation guide or the Advent of Kotlin 2018 exercises.

If you attended any of our courses or courses conducted by Marcin Moskala and you haven’t received any email (check spam), it means we don’t have your email address. Login and then contact us by email contact@kt.academy.

Open workshop request — we know some of you wanted to request an open online workshop in your region, but our website didn’t support that. Now it does! A separate form for the in-company and open workshop requests.

DTO Generator— since in backend applications we need to generate lots of similar classes (dto, json, document/entity, assertion) we made a generator.

JSON formatter — makes JSON pretty and generates TypeScript type as well as Kotlin class definitions. Runs on your browser and does not send or save your code anywhere!

We hope that you like these changes! If you have any suggestions or there is anything else you’d like to share, contact us at contact@kt.academy. We’re happy to help! 🙂

Happy coding!
Kt. Academy Team


New tools on our website was originally published in Kt. Academy on Medium, where people are continuing the conversation by highlighting and responding to this story.

Continue ReadingNew tools on our website

Coding Music

We believe that good concentration music and the Pomodoro technique are great for programming, so we combined them in our new programming music tool.

You can find there great music for programming, set your preferences for work and break time (all values are stored in cookies), recommend and rate tracks.

You will find it on our website under the “Extra tools” button.

You can also customize your recommendations list by adding to favorites or blocking recommendations.

We’ve also thought of those who like to listen to music with all the music tool features but don’t follow the Pomodoro timer! You can just set the break time to 0 and your session will keep running unless you pause it by pausing the video 😉

If you have any suggestions or there is anything else you’d like to share, contact us at contact@kt.academy. We’re happy to help! 🙂

Happy coding!
Kt. Academy Team


Coding Music 🎵 was originally published in Kt. Academy on Medium, where people are continuing the conversation by highlighting and responding to this story.

Continue ReadingCoding Music

iOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

One of the biggest complaints you can find between iOS developers is that sometimes, the feedback loop you have when you are doing some fine-tuning of the UI is long. It produces a new Swift compilation, creates a new binary, then the app gets deployed to the simulator, once that’s done, the system will start the app, and then you will be able to navigate to the right screen to check if those small changes are ok.

Sounds familiar?

Meanwhile, you can see your colleges developing websites or React Native apps that they get feedback almost immediately, and they can even modify the UI with a designer in “real-time.”

Feel any envy yet?

What if I tell you that in iOS, we can achieve something similar to that with almost no effort? Would you believe me?

In Karumi, we’ve been playing a bit with a tool that will help us to hot-swap our code so we can shrink our feedback loop duration to just a couple of seconds.

Injection III to the rescue.

This tool created by John Holdsworth will be the one doing all the magic under the hood; it will be checking which files are being changed, compile them, and dynamically insert that code in your running app. Let’s create a tiny example so we can test how this works.

First, we need to install this app from the AppStore and run it.

HotSwapp.

So, let’s create a brand new iOS project, a “Single View App” with Swift and Storyboards, nothing fancy.

Although Injection III has no issues with Storyboards and xibs, I do ( 😬 ), so let’s get rid of the main storyboard and modify our

ViewController

to contain a label center on the screen.

Now it’s time to setup Injection III to be able to edit our label in real-time.

First, we have to load a bundle into our app that will help us with the method swizzling. In our

AppDelegate

we will add the following lines:


func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         ...
    #if DEBUG
        Bundle(path: "/Applications/InjectionIII.app/Contents/Resources/iOSInjection.bundle")?.load()
     #endif
        ...
    return true
}

then, once the Injection III app is running, we have to open our project in it so it can track any changes in our files.

Re-run your app, and you should see something like:


💉 Injection connected 👍
💉 Watching /Users/Fran/Development/HotSwapp/**

That means that your app is ready to handle code injection at runtime, let’s give it a go. Without stopping the app, change the label text color and save it.

Your Xcode output will display something like:


💉 *** Compiling /Users/Fran/Development/HotSwapp/HotSwapp/ViewController.swift ***
💉 Loading .dylib ...
objc[7606]: Class _TtC8HotSwapp14ViewController is implemented in both /Users/Fran/Library/Developer/CoreSimulator/Devices/5625C398-4862-4C4E-A5AF-E51A78D1113F/data/Containers/Bundle/Application/BDCBDDA4-A09B-4D72-8048-C24FF1193279/HotSwapp.app/HotSwapp (0x101d72a10) and /Users/Fran/Library/Containers/com.johnholdsworth.InjectionIII/Data/eval101.dylib (0x104b19278). One of the two will be used. Which one is undefined.
💉 Loaded .dylib - Ignore any duplicate class warning ^
💉 Injected 'ViewController'

But your app label keeps having the same color, what’s going on?

Your app has a new code, but you have to respond to that change. Create a new file, called it

UIViewController+HotSwap.swift

and add this content:


import UIKit

#if DEBUG
    extension UIViewController {
        @objc func injected() {
            for subview in view.subviews {
                subview.removeFromSuperview()
            }
            if let sublayers = self.view.layer.sublayers {
                for sublayer in sublayers {
                    sublayer.removeFromSuperlayer()
                }
            }

            viewDidLoad()
        }
    }
#endif

What this method is doing is removing all views and layers from your view controller and will invoke the viewDidLoad method again. Stop your app, and rerun it, now it will show the new color.

Now, change the label color and save it.

🎉🎉🎉

Without stopping it, replace one of the constraints to adjust the label to the left border. Once you save it, in one second, the UI will be reflecting that change.

Now imagine that instead of this app, how this could improve your development speed in some scenarios with a big app, with thousands of lines of code with a lot of third parties dependencies.

iOS UI development, ludicrously fast.

Our experience so far.

After using this for a few weeks, we would like to share with you what we’ve learned about this so you can get up to speed without making the same mistakes we did.

  • Check the documentation from the project.
  • This does not work well when there are new methods or properties; in those cases, rebuild the whole app. What we do is define upfront the methods we are going to need, and then we fill them with the logic.
  • Do not create your views outside the viewDidLoad method; otherwise after the first run, the UI could end up in an invalid state. Keep this in mind, viewDidLoad should init every view and their constraints.
  • You cannot use this on a real device.
  • Code swapping does not get along code coverage, so we recommend you to keep a different scheme for the usage of Injection III while you are fine-tuning your UI.

References

Photo by Jean Gerber on Unsplash

Continue ReadingiOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

One of the biggest complaints you can find between iOS developers is that sometimes, the feedback loop you have when you are doing some fine-tuning of the UI is long. It produces a new Swift compilation, creates a new binary, then the app gets deployed to the simulator, once that’s done, the system will start the app, and then you will be able to navigate to the right screen to check if those small changes are ok.

Sounds familiar?

Meanwhile, you can see your colleges developing websites or React Native apps that they get feedback almost immediately, and they can even modify the UI with a designer in “real-time.”

Feel any envy yet?

What if I tell you that in iOS, we can achieve something similar to that with almost no effort? Would you believe me?

In Karumi, we’ve been playing a bit with a tool that will help us to hot-swap our code so we can shrink our feedback loop duration to just a couple of seconds.

Injection III to the rescue.

This tool created by John Holdsworth will be the one doing all the magic under the hood; it will be checking which files are being changed, compile them, and dynamically insert that code in your running app. Let’s create a tiny example so we can test how this works.

First, we need to install this app from the AppStore and run it.

HotSwapp.

So, let’s create a brand new iOS project, a “Single View App” with Swift and Storyboards, nothing fancy.

Although Injection III has no issues with Storyboards and xibs, I do ( 😬 ), so let’s get rid of the main storyboard and modify our

ViewController

to contain a label center on the screen.

Now it’s time to setup Injection III to be able to edit our label in real-time.

First, we have to load a bundle into our app that will help us with the method swizzling. In our

AppDelegate

we will add the following lines:


func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         ...
    #if DEBUG
        Bundle(path: "/Applications/InjectionIII.app/Contents/Resources/iOSInjection.bundle")?.load()
     #endif
        ...
    return true
}

then, once the Injection III app is running, we have to open our project in it so it can track any changes in our files.

Re-run your app, and you should see something like:


💉 Injection connected 👍
💉 Watching /Users/Fran/Development/HotSwapp/**

That means that your app is ready to handle code injection at runtime, let’s give it a go. Without stopping the app, change the label text color and save it.

Your Xcode output will display something like:


💉 *** Compiling /Users/Fran/Development/HotSwapp/HotSwapp/ViewController.swift ***
💉 Loading .dylib ...
objc[7606]: Class _TtC8HotSwapp14ViewController is implemented in both /Users/Fran/Library/Developer/CoreSimulator/Devices/5625C398-4862-4C4E-A5AF-E51A78D1113F/data/Containers/Bundle/Application/BDCBDDA4-A09B-4D72-8048-C24FF1193279/HotSwapp.app/HotSwapp (0x101d72a10) and /Users/Fran/Library/Containers/com.johnholdsworth.InjectionIII/Data/eval101.dylib (0x104b19278). One of the two will be used. Which one is undefined.
💉 Loaded .dylib - Ignore any duplicate class warning ^
💉 Injected 'ViewController'

But your app label keeps having the same color, what’s going on?

Your app has a new code, but you have to respond to that change. Create a new file, called it

UIViewController+HotSwap.swift

and add this content:


import UIKit

#if DEBUG
    extension UIViewController {
        @objc func injected() {
            for subview in view.subviews {
                subview.removeFromSuperview()
            }
            if let sublayers = self.view.layer.sublayers {
                for sublayer in sublayers {
                    sublayer.removeFromSuperlayer()
                }
            }

            viewDidLoad()
        }
    }
#endif

What this method is doing is removing all views and layers from your view controller and will invoke the viewDidLoad method again. Stop your app, and rerun it, now it will show the new color.

Now, change the label color and save it.

🎉🎉🎉

Without stopping it, replace one of the constraints to adjust the label to the left border. Once you save it, in one second, the UI will be reflecting that change.

Now imagine that instead of this app, how this could improve your development speed in some scenarios with a big app, with thousands of lines of code with a lot of third parties dependencies.

iOS UI development, ludicrously fast.

Our experience so far.

After using this for a few weeks, we would like to share with you what we’ve learned about this so you can get up to speed without making the same mistakes we did.

  • Check the documentation from the project.
  • This does not work well when there are new methods or properties; in those cases, rebuild the whole app. What we do is define upfront the methods we are going to need, and then we fill them with the logic.
  • Do not create your views outside the viewDidLoad method; otherwise after the first run, the UI could end up in an invalid state. Keep this in mind, viewDidLoad should init every view and their constraints.
  • You cannot use this on a real device.
  • Code swapping does not get along code coverage, so we recommend you to keep a different scheme for the usage of Injection III while you are fine-tuning your UI.

References

Photo by Jean Gerber on Unsplash

Continue ReadingiOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

One of the biggest complaints you can find between iOS developers is that sometimes, the feedback loop you have when you are doing some fine-tuning of the UI is long. It produces a new Swift compilation, creates a new binary, then the app gets deployed to the simulator, once that’s done, the system will start the app, and then you will be able to navigate to the right screen to check if those small changes are ok.

Sounds familiar?

Meanwhile, you can see your colleges developing websites or React Native apps that they get feedback almost immediately, and they can even modify the UI with a designer in “real-time.”

Feel any envy yet?

What if I tell you that in iOS, we can achieve something similar to that with almost no effort? Would you believe me?

In Karumi, we’ve been playing a bit with a tool that will help us to hot-swap our code so we can shrink our feedback loop duration to just a couple of seconds.

Injection III to the rescue.

This tool created by John Holdsworth will be the one doing all the magic under the hood; it will be checking which files are being changed, compile them, and dynamically insert that code in your running app. Let’s create a tiny example so we can test how this works.

First, we need to install this app from the AppStore and run it.

HotSwapp.

So, let’s create a brand new iOS project, a “Single View App” with Swift and Storyboards, nothing fancy.

Although Injection III has no issues with Storyboards and xibs, I do ( 😬 ), so let’s get rid of the main storyboard and modify our

ViewController

to contain a label center on the screen.

Now it’s time to setup Injection III to be able to edit our label in real-time.

First, we have to load a bundle into our app that will help us with the method swizzling. In our

AppDelegate

we will add the following lines:


func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         ...
    #if DEBUG
        Bundle(path: "/Applications/InjectionIII.app/Contents/Resources/iOSInjection.bundle")?.load()
     #endif
        ...
    return true
}

then, once the Injection III app is running, we have to open our project in it so it can track any changes in our files.

Re-run your app, and you should see something like:


💉 Injection connected 👍
💉 Watching /Users/Fran/Development/HotSwapp/**

That means that your app is ready to handle code injection at runtime, let’s give it a go. Without stopping the app, change the label text color and save it.

Your Xcode output will display something like:


💉 *** Compiling /Users/Fran/Development/HotSwapp/HotSwapp/ViewController.swift ***
💉 Loading .dylib ...
objc[7606]: Class _TtC8HotSwapp14ViewController is implemented in both /Users/Fran/Library/Developer/CoreSimulator/Devices/5625C398-4862-4C4E-A5AF-E51A78D1113F/data/Containers/Bundle/Application/BDCBDDA4-A09B-4D72-8048-C24FF1193279/HotSwapp.app/HotSwapp (0x101d72a10) and /Users/Fran/Library/Containers/com.johnholdsworth.InjectionIII/Data/eval101.dylib (0x104b19278). One of the two will be used. Which one is undefined.
💉 Loaded .dylib - Ignore any duplicate class warning ^
💉 Injected 'ViewController'

But your app label keeps having the same color, what’s going on?

Your app has a new code, but you have to respond to that change. Create a new file, called it

UIViewController+HotSwap.swift

and add this content:


import UIKit

#if DEBUG
    extension UIViewController {
        @objc func injected() {
            for subview in view.subviews {
                subview.removeFromSuperview()
            }
            if let sublayers = self.view.layer.sublayers {
                for sublayer in sublayers {
                    sublayer.removeFromSuperlayer()
                }
            }

            viewDidLoad()
        }
    }
#endif

What this method is doing is removing all views and layers from your view controller and will invoke the viewDidLoad method again. Stop your app, and rerun it, now it will show the new color.

Now, change the label color and save it.

🎉🎉🎉

Without stopping it, replace one of the constraints to adjust the label to the left border. Once you save it, in one second, the UI will be reflecting that change.

Now imagine that instead of this app, how this could improve your development speed in some scenarios with a big app, with thousands of lines of code with a lot of third parties dependencies.

iOS UI development, ludicrously fast.

Our experience so far.

After using this for a few weeks, we would like to share with you what we’ve learned about this so you can get up to speed without making the same mistakes we did.

  • Check the documentation from the project.
  • This does not work well when there are new methods or properties; in those cases, rebuild the whole app. What we do is define upfront the methods we are going to need, and then we fill them with the logic.
  • Do not create your views outside the viewDidLoad method; otherwise after the first run, the UI could end up in an invalid state. Keep this in mind, viewDidLoad should init every view and their constraints.
  • You cannot use this on a real device.
  • Code swapping does not get along code coverage, so we recommend you to keep a different scheme for the usage of Injection III while you are fine-tuning your UI.

References

Photo by Jean Gerber on Unsplash

Continue ReadingiOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

iOS UI development, ludicrously fast.

One of the biggest complaints you can find between iOS developers is that sometimes, the feedback loop you have when you are doing some fine-tuning of the UI is long. It produces a new Swift compilation, creates a new binary, then the app gets deployed to the simulator, once that’s done, the system will start the app, and then you will be able to navigate to the right screen to check if those small changes are ok.

Sounds familiar?

Meanwhile, you can see your colleges developing websites or React Native apps that they get feedback almost immediately, and they can even modify the UI with a designer in “real-time.”

Feel any envy yet?

What if I tell you that in iOS, we can achieve something similar to that with almost no effort? Would you believe me?

In Karumi, we’ve been playing a bit with a tool that will help us to hot-swap our code so we can shrink our feedback loop duration to just a couple of seconds.

Injection III to the rescue.

This tool created by John Holdsworth will be the one doing all the magic under the hood; it will be checking which files are being changed, compile them, and dynamically insert that code in your running app. Let’s create a tiny example so we can test how this works.

First, we need to install this app from the AppStore and run it.

HotSwapp.

So, let’s create a brand new iOS project, a “Single View App” with Swift and Storyboards, nothing fancy.

Although Injection III has no issues with Storyboards and xibs, I do ( 😬 ), so let’s get rid of the main storyboard and modify our

ViewController

to contain a label center on the screen.

Now it’s time to setup Injection III to be able to edit our label in real-time.

First, we have to load a bundle into our app that will help us with the method swizzling. In our

AppDelegate

we will add the following lines:


func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         ...
    #if DEBUG
        Bundle(path: "/Applications/InjectionIII.app/Contents/Resources/iOSInjection.bundle")?.load()
     #endif
        ...
    return true
}

then, once the Injection III app is running, we have to open our project in it so it can track any changes in our files.

Re-run your app, and you should see something like:


💉 Injection connected 👍
💉 Watching /Users/Fran/Development/HotSwapp/**

That means that your app is ready to handle code injection at runtime, let’s give it a go. Without stopping the app, change the label text color and save it.

Your Xcode output will display something like:


💉 *** Compiling /Users/Fran/Development/HotSwapp/HotSwapp/ViewController.swift ***
💉 Loading .dylib ...
objc[7606]: Class _TtC8HotSwapp14ViewController is implemented in both /Users/Fran/Library/Developer/CoreSimulator/Devices/5625C398-4862-4C4E-A5AF-E51A78D1113F/data/Containers/Bundle/Application/BDCBDDA4-A09B-4D72-8048-C24FF1193279/HotSwapp.app/HotSwapp (0x101d72a10) and /Users/Fran/Library/Containers/com.johnholdsworth.InjectionIII/Data/eval101.dylib (0x104b19278). One of the two will be used. Which one is undefined.
💉 Loaded .dylib - Ignore any duplicate class warning ^
💉 Injected 'ViewController'

But your app label keeps having the same color, what’s going on?

Your app has a new code, but you have to respond to that change. Create a new file, called it

UIViewController+HotSwap.swift

and add this content:


import UIKit

#if DEBUG
    extension UIViewController {
        @objc func injected() {
            for subview in view.subviews {
                subview.removeFromSuperview()
            }
            if let sublayers = self.view.layer.sublayers {
                for sublayer in sublayers {
                    sublayer.removeFromSuperlayer()
                }
            }

            viewDidLoad()
        }
    }
#endif

What this method is doing is removing all views and layers from your view controller and will invoke the viewDidLoad method again. Stop your app, and rerun it, now it will show the new color.

Now, change the label color and save it.

🎉🎉🎉

Without stopping it, replace one of the constraints to adjust the label to the left border. Once you save it, in one second, the UI will be reflecting that change.

Now imagine that instead of this app, how this could improve your development speed in some scenarios with a big app, with thousands of lines of code with a lot of third parties dependencies.

iOS UI development, ludicrously fast.

Our experience so far.

After using this for a few weeks, we would like to share with you what we’ve learned about this so you can get up to speed without making the same mistakes we did.

  • Check the documentation from the project.
  • This does not work well when there are new methods or properties; in those cases, rebuild the whole app. What we do is define upfront the methods we are going to need, and then we fill them with the logic.
  • Do not create your views outside the viewDidLoad method; otherwise after the first run, the UI could end up in an invalid state. Keep this in mind, viewDidLoad should init every view and their constraints.
  • You cannot use this on a real device.
  • Code swapping does not get along code coverage, so we recommend you to keep a different scheme for the usage of Injection III while you are fine-tuning your UI.

References

Photo by Jean Gerber on Unsplash

Continue ReadingiOS UI development, ludicrously fast.

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