Android 10 messed up royally with removing the API to add networks and connect to it on a users device. The API was removed and as an alternative they gave us:

1. A suggestion API, which shows a low priority notification, suggesting to connect to a given network. This notification would need to be swiped down a couple of times to reveal the YES/NO options. Then the device might choose not to connect to it anyways.
2. A way to connect to a local network, not providing any Internet connectivity, through a System dialog appearing in the App. This dialog took forever to find your network. However, this method was not very useful for anyone as no Internet on this connection.

The last alternative, but technically not a part of the API for connecting to WiFi, would be to show a settings panel, where the user could manually enter credentials for a WiFi network in the list.

New Android 11 API

Note: this code will throw a ActivityNotFoundException if run on older Android versions. Make sure to add some version checking.

I guess the folks at Google got a bit backlash or they somehow changed their mind. However, they’ve now added an Intent you can fire to add a Network on the device.

The code for this looks something like this:

var intent = new Intent(
    "android.settings.WIFI_ADD_NETWORKS");
var bundle = new Bundle();
bundle.PutParcelableArrayList(
    "android.provider.extra.WIFI_NETWORK_LIST",
    new List<IParcelable>
    {
        new WifiNetworkSuggestion.Builder()
            .SetSsid(ssid)
            .SetWpa2Passphrase(password)
            .Build()
    });

intent.PutExtras(bundle);

StartActivityForResult(intent, AddWifiSettingsRequestCode);

Note: AddWifiSettingsRequestCode is just an Integer you define.

Then in OnActivityResult you can figure out whether any network in the list you provided was added with:

if (requestCode == AddWifiSettingsRequestCode)
{
    if (data != null && data.HasExtra(
        "android.provider.extra.WIFI_NETWORK_RESULT_LIST"))
    {
        var extras =
            data.GetIntegerArrayListExtra(
                "android.provider.extra.WIFI_NETWORK_RESULT_LIST")
                ?.Select(i => i.IntValue()).ToArray() ?? new int[0];

        if (extras.Length > 0)
        {
            var ok = extras
                .Select(GetResultFromCode)
                .All(r => r == Result.Ok);
            // if ok is true, BINGO!
            return;
        }
    }
}

The extras will return a list of Result which indicate whether they were added if it is Result.OK or not if it is Result.Cancel.

GetResultFromCode, simply parses the integers returned and turns them into a Result:

private static Result GetResultFromCode(int code) =>
    code switch
    {
        0 => Result.Ok, // newly added
        2 => Result.Ok, // wifi already there
        _ => Result.Canceled
    };

Running this code will show you a dialog looking something like this

Note: This code works and runs fine on a Google Pixel 3a XL running latest Android 11. However, on my OnePlus 8 running OP8_O2_BETA_3 opening the intent fails, because of OnePlus’s Settings App does not implement the AppCompat theme, crashing. I’ve reported this issue to OnePlus but never heard back from them.

You can check out the code from my Android 11 WiFi Repository on GitHub and have a go testing it yourself.

If you are looking for samples scroll down to the bottom of this blog post

I have gotten questions from multiple people, about versions of MvvmCross prior to version 6.4.1. What they can do about being forced to target Android 10, API 29, or newer from November 2nd, when Google stops accepting updates to Apps targeting lower API levels.

MvvmCross 6.4.1 introduced some changes to MvxLayoutInflater that are needed in order for it to work with Android 10. However, these changes are for obvious reasons not part of previous releases.

Luckily MvvmCross is written in a way where you can replace parts of it through virtual methods and implementing certain interfaces. This can be used to retrofit old versions of MvvmCross with newer patched versions of, in this case, MvxLayoutInflater.

You simply have to follow these 3 simple steps!

1. Go to the corner
2. Curl up in a ball
3. Cry 😭

Sorry, wait, no. Thats not it! Upgrade MvvmCross! But, if you really cannot upgrade then try these steps.

1. Grab latest MvxLayoutInflater
2. Create your own implementation of MvxContextWrapper which uses 1.
3. Create your own MvxActivity derivatives that uses ContextWrapper from 2.
4. Replace all MvxActivities with your own

OK, I lied that was 4 steps. You might also need a 5th step, where you target Android 10 in your App, otherwise all this work will be useless anyways…

Lets go through all steps.

1. Get latest MvxLayoutInflater

Grab latest MvxLayoutInflater and MvxLayoutInflaterCompat, change namespace to something more suitable in your App. Rename the class FixedLayoutInflater or whatever you prefer.

2. Create your own implementation of MvxContextWrapper

We have to supply our own MvxContextWrapper class, the code in there is super simple. It just tells Android which LayoutInflater to use. We want to use our FixedLayoutInflater in there.

using System;
using Android.Content;
using Android.Runtime;
using Android.Views;
using MvvmCross.Binding.BindingContext;
using Object = Java.Lang.Object;

namespace Awesome.App
{
    [Register("awesome.app.FixedContextWrapper")]
    public class FixedContextWrapper : ContextWrapper
    {
        private LayoutInflater _inflater;
        private readonly IMvxBindingContextOwner _bindingContextOwner;

        public static ContextWrapper Wrap(Context @base, IMvxBindingContextOwner bindingContextOwner)
        {
            return new FixedContextWrapper(@base, bindingContextOwner);
        }

        protected FixedContextWrapper(Context context, IMvxBindingContextOwner bindingContextOwner)
            : base(context)
        {
            if (bindingContextOwner == null)
                throw new InvalidOperationException("Wrapper can only be set on IMvxBindingContextOwner");

            _bindingContextOwner = bindingContextOwner;
        }

        public override Object GetSystemService(string name)
        {
            if (string.Equals(name, LayoutInflaterService, StringComparison.InvariantCulture))
            {
                return _inflater ??=
                    new FixedLayoutInflater(LayoutInflater.From(BaseContext), this, null, false);
            }

            return base.GetSystemService(name);
        }
    }
}

3. Create your own MvxActivity derivate

Next step is to create your own MvxActivity derivate. Why? Because you need to supply that ContextWrapper we just created. If you were to simply inherit from MvxActivity and override OnAttachContext, which is where we supply the ContextWrapper, then it would still use the original MvxContextWrapper, since the only way to supply it is by calling base.OnAttachContext.

OK. So yank whatever MvxActivity type you are re-implementing. Here is a non-exhaustive list of types we had.

The part to replace is the contents of OnAttachContext which should look something like:

protected override void AttachBaseContext(Context @base)
{
    if (this is IMvxAndroidSplashScreenActivity)
    {
        // Do not attach our inflater to splash screens.
        base.AttachBaseContext(@base);
        return;
    }
    base.AttachBaseContext(FixedContextWrapper.Wrap(@base, this));
}

With that done, now you just have to replace every inheritance from MvxActivity in your App with this implementation, except for any splash screens, not needed there.

You may have to think a bit here and modify the code to your needs, but these are the simplest steps I could come up with.

You can find sample projects with fixes implemented on my GitHub in the repository OldMvvmCross-Android10

This blog post is a part of Louis Matos’s Xamarin Month, where this months topic is Code Snippets. For more information take a look at his blog and see the list of all the other auhtors who are participating. There will be a new post each day of the month, which is super cool!

Let me share some code snippets that I often use. All of these snippets will be available in my XamarinSnippets code repository on GitHub, for import in Visual Studio 2019, ReSharper, Rider and Visual Studio for Mac. Instructions provided in the repository Readme file.

When writing an Application using MvvmCross, or even with other frameworks, there are some pieces of code that you have to repeat again and again. As programmers we are usually a bit lazy and don’t want to type all that code over and over again. Fortunately, we can have code snippets ready to help us, a nice feature built into our IDE’s. Some of the snippets I use often are as follows.

mvxprop

I often have to create a property in my ViewModels which raise the PropertyChanged event in the MvvmCross flavor. For that I simply type mvxprop and press Tab, and magically I get the following code.

private int propertyName;
public int PropertyName
{
    get => propertyName;
    set => SetProperty(ref propertyName, value);
}

I have considered making some flavors for some common types that I use, such as string, bool, int. Not sure how much I would use them.

mvxcom

Creating commands is also something that I often do. However, I’ve gone away from using this pattern where I lazily initialize commands, some of you may find them useful. What I prefer instead is initialize them in the constructor of the ViewModel instead.

private MvxCommand _command;
public MvxCommand Command =>
    _command ??= new MvxCommand(DoCommand);

private void DoCommand()
{
    // do stuff
}

I have a couple of variants of this snippet, which creates different types of MvxCommand. mvxcomt for the generic MvxCommand<T>, mvxcomasync for the async version MvxAsyncCommand and similarly the generic version of that mvxcomtasync which creates a MvxAsyncCommand<T>.

mvxbset

Last but not least, a snippet for creating a binding set for binding views on both Android and iOS. I’ve taken the liberty to make the assumption that View and ViewModel names follow each other. So PeopleView will usually have a corresponding ViewModel PeopleViewModel. This ends up creating something like this:

using var set = this.CreateBindingSet<PeopleView, PeopleViewModel>();

Get all the snippets along with instructions in my XamarinSnippets repository on GitHub.

Do you have any cool related MvvmCross snippets to share? Put them in the comments or make a Pull Request on the repository.

Some years ago I ported over some Java color pickers to work with Xamarin. However, it didn’t really cross my mind to release these as a NuGet package. However, due to demand I finally took the time to do so.

You can find the NuGet package here: https://www.nuget.org/packages/Cheesebaron.ColorPickers/

The source code as usual is available on GitHub: https://github.com/Cheesebaron/Cheesebaron.ColorPickers

Here is a couple of screen shots of what you can expect from the library.

I just had the task to figure out why we had an App crashing randomly on us all of the sudden. The App is distrubuted through AppCenter only, as a Enterprise build. Turned out that the provisioning profile had expired hence it started to fail.

Now, I did not want to build a new version of the App, since the one distributed and in production is much older and we are in the middle of moving CI for the App into a new enviroment. So the only option was to sign the App again with the new provisioning profile. So here are some notes on how I did that.

The prerequisites for this are:

• IPA file to re-sign
• Distribution certificate is installed in your KeyChain
• mobileprovision file to sign with
• a macOS installation with Xcode installed (I used 11.3.1)

The following snippets are commands you would run in your preferred commandline.

First we need to unizp the IPA file. It will contain a Payload folder with AppName.app inside, where AppName is your App’s name. I will use MyApp as an example throughout this post. Yours will of course be different.

unzip MyApp.ipa

You should now have a Payload folder where contents were extracted.

First we need to extract the entitlements for the App, we will need them later when we are signing the App again.

codesign -d --entitlements :- "Payload/MyApp.app" > entitlements.plist

This will create a entitlements.plist file in the folder you are currently in. If you are re-signing the App with a distribution certificate for another team, remember to change identifiers in the entitlements file to match your distribution certificate.

Now before we re-sign the App, we need to remove the old code signing.

rm -r Payload/MyApp.app/_CodeSignature

We also need to replace the provisioning profile. Assuming your profivisioning profile file name is called MyApp.mobileprovision and is located in the same folder we are in.

cp MyApp.mobileprovision Payload/MyApp.app/embedded.mobileprovision

We should now be ready to re-sign the Application.

codesign -f -s "iPhone Distribution: your team name here" --entitlements entitlements.plist Payload/MyApp.app

Now we just need to zip the folder and we are ready to distribute it.

zip -qr MyApp-resigned.ipa Payload

That is it! You are ready to ship your re-signed App!