Xamarin.Tip – iOS Push Notification Device Token Extraction in iOS 13+

This weekend, I spent some time getting some apps updated with the latest Xamarin, iOS, Android, etc. A lot of these apps make use of push notifications across platforms. I was running some automated tests against them to do the following steps:

  • Register for push notifications on sign-in / startup
  • Send registration update details to API
  • API sends updates to Azure Notification Hub or Firebase (depends on the project)
  • Send push notification to all test users
  • Send push notification to specific test user

I noticed immediately that all my new iOS builds were failing to receive any push notifications after updating registrations.

Time to debug!

The Old Way

Here was my original method for kicking off the push notification registration:

AppDelegate.cs

//...
private void RegisterForPush()
{
    if (UIDevice.CurrentDevice.CheckSystemVersion(10, 0))
    {
        UNUserNotificationCenter.Current.RequestAuthorization(UNAuthorizationOptions.Alert | UNAuthorizationOptions.Badge | UNAuthorizationOptions.Sound,
            (granted, error) =>
            {
                if (granted)
                    InvokeOnMainThread(UIApplication.SharedApplication.RegisterForRemoteNotifications);
            });
    }
    else if (UIDevice.CurrentDevice.CheckSystemVersion(8, 0))
    {
        var pushSettings = UIUserNotificationSettings.GetSettingsForTypes(
                UIUserNotificationType.Alert | UIUserNotificationType.Badge | UIUserNotificationType.Sound,
                new NSSet());

        UIApplication.SharedApplication.RegisterUserNotificationSettings(pushSettings);
        UIApplication.SharedApplication.RegisterForRemoteNotifications();
    }
    else
    {
        UIRemoteNotificationType notificationTypes = UIRemoteNotificationType.Alert | UIRemoteNotificationType.Badge | UIRemoteNotificationType.Sound;
        UIApplication.SharedApplication.RegisterForRemoteNotificationTypes(notificationTypes);
    }
}
// ..

This processes kicks off the internal iOS process to start registration. It will check against your apps registered entitlements for push, check the environment it should be using between development and production, and then if all goes well, it will hit the RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken) method in the AppDelegate. If there are any explicit errors it will instead hit FailedToRegisterForRemoteNotifications(UIApplication application, NSError error).

So what we need is the data within that deviceToken of the RegisteredForRemoteNotifications method to send to our API.

Here is what the ORIGINAL implementation looked like (with some of the abstractions removed for simplicity):

AppDelegate.cs

// non-user registration
public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
{
    // if using default registration with notification hub for non-user apps
    Hub = new SBNotificationHub("{CONN_STRING}", "{AZURE_HUB_NAME}");

    Hub.UnregisterAll(deviceToken, (error) =>
    {
        if (error != null)
        {
            System.Diagnostics.Debug.WriteLine("Error calling Unregister: {0}", error.ToString());
            return;
        }

        NSSet tags = null; // create tags if you want
        Hub.RegisterNativeAsync(deviceToken, tags);

    });
}

And for handling specific user registration, we need to send it to the API:

AppDelegate.cs

public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
{
    var token = deviceToken?.Description?.Trim('<', '>')?.Replace(" ", string.Empty);
    if (!string.IsNullOrEmpty(token))
    {
        // this sends the handle to the API to do all the registration
        var remoteRegistrar = new RemoteNotificationRegistrar();
        remoteRegistrar.RegisterForPushAsync("apns", token);
    }
}

Debugging showed me the issue was here:

var token = deviceToken?.Description?.Trim('<', '>')?.Replace(" ", string.Empty);

The token was no longer in the same format… Feeling like an idiot who has been out of the loop, I hit the internet to see what I missed and landed on some of these lovely articles and posts:

So lets do this update in Xamarin:

The New Way

So the old token structure looked like this:

And the new token looks like this:

{length = 32, bytes = 0x965b251c 6cb1926d e3cb366f dfb16ddd ... 5f857679 376eab7c }

So basically we need a clean version of that bytes property of the NSData object.

Azure notification hubs already do this behind the scenes, but we need the clean version for our own method to send to our API, so here’s the new version:

AppDelegate.cs

public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
{
    var token = ExtractToken(deviceToken);
    if (!string.IsNullOrEmpty(token))
    {
        // this sends the handle to the API to do all the registration
        var remoteRegistrar = new RemoteNotificationRegistrar();
        remoteRegistrar.RegisterForPushAsync("apns", token);
    }
}

private string ExtractToken(NSData deviceToken)
{
    if (deviceToken.Length == 0)
        return null;
    var result = new byte[deviceToken.Length];
    System.Runtime.InteropServices.Marshal.Copy(deviceToken.Bytes, result, 0, (int)deviceToken.Length);
    return BitConverter.ToString(result).Replace("-", "");
}

There are a few different ways to write this ExtractToken method, but this is what has worked for me!.

After making this change and running it on iOS 13, I started getting user notifications again!

Both Ways

This is great and all, but I still want to make sure folks who haven’t updated to iOS 13 can still use my apps, so I added some explicit version checks to decide which way to extract the token. Here’s what the final looks like all within that ExtractToken method:

private string ExtractToken(NSData deviceToken)
{
    if(UIDevice.CurrentDevice.CheckSystemVersion(13,0))
    {
        if(deviceToken.Length > 0)
        {
            var result = new byte[deviceToken.Length];
            Marshal.Copy(deviceToken.Bytes, result, 0, (int)deviceToken.Length);
            return BitConverter.ToString(result).Replace("-", string.Empty);
        }
    }
    else 
    {
        return deviceToken.Description.Trim('<', '>');
    }

    return null;
}

And that’s it! Try this out if you’re having issues with the latest iOS 13 update and your push notification registration.

If you’re still having problems with push notification registration in general, leave a comment below! I’d love to put together an article about the common pitfalls of push notifications on both iOS and Android with a checklist of things to look at, fix, or build on top of what you have!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile and AI developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.


CodeMash 2020 This Week!

This week I’ll be at CodeMash – an amazing developer event at the Kalahari Resort in Ohio. CodeMash holds a special place in my heart; It’s the first developer conference I ever attended, the first I ever sponsored, and now I have the honor of being a speaker!

This year, I’ll be talking more about Kotlin for C# developers, and you can catch the session at 9:15 am on Thursday.

Annotation 2020-01-06 113339

If you’re looking to expand your language portfolio with something familiar yet new as a C# developer, you’re going to love this session. Learn about the Kotlin programming language side-by-side with C#, compare and contrast both languages’ amazing features and tooling and walk away with the confidence to to explore and build more with both languages and stacks.

Check out the schedule and other speakers here: https://www.codemash.org/

If you’re at the conference or the area, let me know! I’d love to chat.


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Xamarin.Tip – Fixing Missing iOS App Icons

In the age of Xamarin Hot Reload and Hot Restart, we are beginning to get spoiled with the tooling we use every day. I find myself spending less and less time dealing with workarounds for Xamarin issues, filing bug reports, or getting frustrated at not understanding why something isn’t working.

Until today…

The issue – I created an AppIcon for my iOS app, and it simply won’t show up on any device or simulator. I had seen this before, so I double checked everything and tried all my old tricks:

  • Check that the AppIcon asset was in the Assets.xcassets
  • Check that the actual AppIcon had all the images filled in
  • Check that my info.plist was pointing at my AppIcon
  • Clean
  • Rebuild
  • Clear all caches
  • Restart VS
  • Restart machine
  • Try on another machine, repeat above steps
  • Panic

Nothing. So, if you’re new to Xamarin development or iOS development in general, the above steps are definitely the first things to try!

One thing I did differently this time around was use https://makeappicon.com/ to generate my individual icons from a single high resolution image. Usually the designer on my team will send me the exact icons exported to the specific sizes, but they were on vacation and I wanted to make some progress! I 100% recommend using MakeAppIcon for those who haven’t discovered it yet.
For those that haven’t used it, MakeAppIcon gives you a zip with the actual AppIcon.appiconset which includes every size you need and their registration in the Contents.json which tells the build agent what images fit which profile/size. This Contents.json is also what Visual Studio uses to show you the icons in your Assets.xcassets.

So all you have to do is take the AppIcon.appiconset and drop it in your Assets.xcassets and you’re off and running. Or so I thought…

Turns out VS uses the Content.json to read the images to show in your assets, but this does not actually include them in any sort of build output to your final .ipa – so we need to actually update our ios project’s .csproj file to make sure all the images and their full paths are included – not just the AppIcon.appiconset. Normally, if you drag and drop or file select within Visual Studio to set the images for your app icon, this is done for you. But if you bring in your icons from any outside source, be sure to make sure you add them in the .csproj – something like this:

<ImageAsset Include="Assets.xcassets\AppIcons.appiconset\Contents.json">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Contents.json">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-20x20@1x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-20x20@2x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-20x20@3x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-29x29@1x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-29x29@2x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-29x29@3x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-40x40@1x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-40x40@2x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-40x40@3x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-60x60@2x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-20x20@1x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-60x60@3x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-76x76@1x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-76x76@2x.png">
  <Visible>false</Visible>
</ImageAsset>
<ImageAsset Include="Assets.xcassets\AppIcon.appiconset\Icon-App-83.5x83.5@2x.png">
  <Visible>false</Visible>
</ImageAsset>

Long story short – copy paste this into your .csproj if you use MakeAppIcon and save yourself some time. If this didn’t help you or isn’t why your App icon isn’t showing up, here are some links I’ve used in the past:
https://stackoverflow.com/questions/48375681/ios-app-icon-missing-on-ios-11
https://xamarin.github.io/bugzilla-archives/59/59515/bug.html
https://docs.microsoft.com/en-us/xamarin/ios/app-fundamentals/images-icons/app-store-icon
https://blog.rthand.com/post/2017/10/17/app-icons-missing-after-upgrading-to-ios-11-xamarin.aspx


More meaningful and useful content coming soon! Including more Alexa, Dialogflow, Google Assistant, Bixby, Cortana, and of course Xamarin work 🙂


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Meadow.Tip – Playing Jingle Bells with a Piezo Speaker Using C#

I was lucky enough to be one of the early backers of the new Meadow board series from Wilderness labs and have since received my board as well as Hack Kit Pro! In this series, I explore and share some of the things I built for fun or for real. Check out wilderness labs here: https://www.wildernesslabs.co/

Playing Jingle bells

One of the basic samples of using the Meadow.Foundation SDK was playing a single note on repeat using a Piezo speaker. Peep that here: https://github.com/WildernessLabs/Meadow.Foundation/tree/master/Source/Samples/Speakers/PiezoSpeaker_Sample

Where the main class that implements the communication to the speaker is:

public class PiezoSpeakerApp : App<F7Micro, PiezoSpeakerApp>
{
    readonly IDigitalOutputPort port;
    readonly IPwmPort pwm; 
    readonly PiezoSpeaker piezoSpeaker;

    public PiezoSpeakerApp()
    {
        pwm = Device.CreatePwmPort(Device.Pins.D05);
        piezoSpeaker = new PiezoSpeaker(pwm);

        TestPiezoSpeaker();
    }

    protected void TestPiezoSpeaker()
    {
        while (true)
        {
            Console.WriteLine("Playing A4 note!");
            piezoSpeaker.PlayTone(440, 1000);
            piezoSpeaker.StopTone();
            Thread.Sleep(500);
        }
    }
}

The application builds a reference to the Piezo speaker through the Digital 05 port and ground, then proceeds to blast the A4 note on repeat until your ears bleed. This is a nice tool to use to make sure your circuit is setup properly, but I wasn’t satisfied…

As a musician, I’m always on the hunt for pleasant notes, little riffs, chords, etc. So naturally, I started looking up some note frequencies I didn’t know off the top of my head and stringing them together.

One of the first songs guitarists learn when first picking at strings and learning the fretboard is Jingle Bells! So what a great way to teach myself how to develop basic melodies using a single output speaker and my brand new Meadow F7 Micro! With that in mind, you can find the entire source for the app here: https://github.com/SuavePirate/Meadow-Piezo-JingleBells

And here’s the guts of the main jingle bells class for the meadow app:

JingleBellsApp.cs

public class JingleBellsApp : App<F7Micro, JingleBellsApp>
{
    readonly PiezoSpeaker piezoSpeaker;

    const int LENGTH = 26;
    const string NOTES = "eeeeeeegcde fffffeeeeddedg";
    readonly int[] BEATS = { 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2 };
    const int TEMPO = 300;

    public JingleBellsApp()
    {
        piezoSpeaker = new PiezoSpeaker(Device.CreatePwmPort(Device.Pins.D05));

        PlayJingleBells();
    }

    protected void PlayJingleBells()
    {
        while (true)
        {
            Console.WriteLine("Playing jingle bells!");
            for (int i = 0; i < LENGTH; i++)
            {
                if (NOTES[i] == ' ')
                {
                    Thread.Sleep(BEATS[i] * TEMPO); // rest
                }
                else
                {
                    PlayNote(NOTES[i], BEATS[i] * TEMPO);
                }

                // pause between notes
                Thread.Sleep(TEMPO / 2);
            }
            Console.WriteLine("From the top!");
        }
    }
    void PlayNote(char note, int duration)
    {
        char[] names = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' };
        int[] tones = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 };

        // play the tone corresponding to the note name
        for (int i = 0; i < names.Length; i++)
        {
            if (names[i] == note)
            {
                piezoSpeaker.PlayTone(tones[i], duration);
            }
        }
    }
}

I wanted to make the song more configurable, so I broke the melody out into the notes as a string, and the beats for the song to go along with it. You can also play with the TEMPO to speed things up or slow them down. I also built a private PlayNote method that takes in the major note character and the duration and executes the MeadowFoundation piezoSpeaker.PlayTone to execute the tone on the speaker that was initialized earlier in the contstructor.

So with all these things together, the PlayJingleBellsMethod() takes those constant values and the initialized piezoSpeaker and infinitely loops the entire song. Within the while loop, we use a for loop to play the number of beats that we registered in the LENGTH const and proceed to pull out the beats and notes from the arrays above to string the song together.

When setting up the circuit for your Piezo speaker, just make sure you have the black wire to ground on your board, and red to the port you registered in your constructor (in this case D05). Here’s a fritzing diagram of a simple setup for it:

jinglebells_spiezo_bb

That’s all there is to it! Stay tuned for more fun projects and how to setup them up as I keep working through how to build some different fun things with my new Meadow board!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile and AI developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.


voicify_logo
I’m the Director and Principal Architect over at Voicify. Learn how you can use the Voice Experience Platform to bring your brand into the world of voice on Alexa, Google Assistant, Cortana, chat bots, and more: https://voicify.com/


Techorama This Week – Kotlin, C#, Flux, Design Patterns, and more!

If you’re in the Netherlands this week, come catch me at Techorama! I’ll be there from the 30th through the 3rd of October and presenting two different sessions:

techorama_sessions

On the 1st, I’ll be speaking on Kotlin for C# Developers:

Dive into the latest craze in languages and platforms – Kotlin. This time we will be looking at it from the perspective of a .NET C# developer, draw comparisons between the languages, and bridge the gap between these 2 amazing languages. We’ll look at: – Kotlin as a language – Platforms Kotlin is great for – Object Oriented Implementations in Kotlin – Extended Features – Features Kotlin has that C# doesn’t – A demo Android application in Kotlin vs a Xamarin.Android app in C# In the end you will leave with a foundational knowledge of Kotlin and its capabilities to build awesome apps with less code. You should feel comfortable comparing C# applications to Kotlin applications and know where to find resources to learn even more!
And on the 2nd I have another morning session on implementing the Flux design pattern in C# and .NET:
Learn about the Flux design pattern and how to implement it in your C# client applications like UWP, Xamarin, and all the other platforms .NET is touching now. We’ll compare Flux and Uni-Directional data flows to the existing tools and directions development takes us in C# client apps and talk about all the pros and cons that come with both. We’ll take an existing Xamarin.Forms app using MVVM and “Flux it Up” to migrate to a more 1-direction flow of data and actions. When you leave, you’ll have a solid understanding of Flux and some of its existing implementations such as Redux and be confident in implementing it yourself in C#!

Pre-conference Meetup

If you’re not going to Techorama this year, but are still in the area, you can find me tomorrow at the Dutch Mobile .NET Developers meetup with some of the other amazing people from the Xamarin and .NET Community. I’ll be on a panel talking about mobile technologies and practices!

2019 Meetup – Xamarin with David Ortinau & Mobile Expert Panel

Monday, Sep 30, 2019, 6:00 PM

Info Support
Kruisboog 42 Veenendaal, NL

50 Code monkeys Attending

18:00 Doors open & Dinner 19:00 – 20:00 *The Latest and Craziest for Mobile .NET Developers* David Ortinau @davidortinau Microsoft has been hard at work improving Visual Studio and Xamarin for mobile developers. I’ll demo the latest features you can use to make your dev experience better today. And in the future? Microsoft has some “coming soon” as…

Check out this Meetup →

 

Here’s the schedule:

18:00 Doors open & Dinner
19:00 – 20:00 The Latest and Craziest for Mobile .NET Developers
David Ortinau @davidortinau
Microsoft has been hard at work improving Visual Studio and Xamarin for mobile developers. I’ll demo the latest features you can use to make your dev experience better today. And in the future? Microsoft has some “coming soon” as well as highly experimental projects that are “must see”!

20:00 – 20:15 Break
20:15 – 21:00 Mobile Expert Panel with Alex, Brandon, Dan & Gerald
Open Q&A for these mobile experts that have absolutely made their mark in the mobile developer space. This is your chance to ask anything you’d like! Joining us are:

Alex Dunn @suave_pirate
Author at Pluralsight | Xamarin MVP | Microsoft MVP

Brandon Minnick @thecodetraveler
Microsoft Developer Advocate | Mobile App Developer

Dan Siegel @danjsiegel
Microsoft MVP | @PrismLib Maintainer | Xamarin Evangelist | @XamDevSummit Organizer

Gerald Versluis @jfversluis
Engineer @Microsoft for #XamarinForms | Former Microsoft MVP

21:00 Drinks & Closing

 

See ya’ll there!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

HACKMIT 2019 This Weekend!

HackMIT is this weekend, September 14-15th.

I’m happy to announce that I’ll be mentoring as one of the local Microsoft MVPs that were invited to help as part of the Microsoft sponsorship of the event. I look forward to building some incredible applications with some of the brightest students coming to Cambridge! Hack for a reason 🙂

Check out some of the awesome tracks:

hackmit_tracks

 

If you’re hacking this weekend, come find me for help with:

  • Conversational AI
  • Voice First Development
  • Azure
  • AWS
  • Machine Learning
  • Unity
  • C#
  • JavaScript/TypeScript
  • Kotlin
  • React
  • Video Editing
  • and RTC

See ya’ll there!


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.

Video – Kotlin for C# Developers at NDC Oslo

In June, I had the amazing privilege of giving a talk at NDC Oslo called “Kotlin for C# Developers”! Lucky for you, NDC records all of their sessions, so you can check out the recording from YouTube right here 🙂

Dive into the latest craze in languages and platforms – Kotlin. This time we will be looking at it from the perspective of a .NET C# developer, draw comparisons between the languages, and bridge the gap between these 2 amazing languages.

We’ll look at:
– Kotlin as a language
– Platforms Kotlin is great for
– Object Oriented Implementations in Kotlin
– Extended Features
– Features Kotlin has that C# doesn’t
– A demo Android application in Kotlin vs a Xamarin.Android app in C#

In the end you will leave with a foundational knowledge of Kotlin and its capabilities to build awesome apps with less code. You should feel comfortable comparing C# applications to Kotlin applications and know where to find resources to learn even more!

Let me know your thoughts in the comments or on Twitter, and check out my other content on Kotlin here: https://alexdunn.org/tag/kotlin/

Want to see this live? I’ll be giving an updated version of this talk at Techorama Netherlands in September/October along with an introduction to the Flux design pattern in C#.

Check those out here:

If you prefer to just jump right into a language / platform – I would happily suggest my Pluralsight course – Building Android Apps with Kotlin: Getting Started. Take a look here: https://app.pluralsight.com/library/courses/building-android-apps-kotlin-getting-started/

 

 


If you like what you see, don’t forget to follow me on twitter @Suave_Pirate, check out my GitHub, and subscribe to my blog to learn more mobile and AI developer tips and tricks!

Interested in sponsoring developer content? Message @Suave_Pirate on twitter for details.


voicify_logo
I’m the Director and Principal Architect over at Voicify. Learn how you can use the Conversation Experience Platform to bring your brand into the world of voice on Alexa, Google Assistant, Cortana, chat bots, and more: https://voicify.com/