# Fixing push notifications on Android 8. Aka channels

Android 8 (API level 26) expects any notification to use a [Channel](https://developer.android.com/training/notify-user/channels). So we need to implement them but only when the API level is 26+. Channels should be ignored otherwise because they won´t be available, meaning that your app will throw an exception if you try to use them.

We will create a default channel to be used when any push notification arrives. You can create multiple channels but I bet most applications will be just fine with one.

```csharp
public static class NotificationHelper 
{ 
    public const string ChannelId = "com.unique.string.onyourapp.default";
    
    // make sure you call this method only once 
    public static void CreateDefaultChannel(Context context) 
    { 
        if (Build.VERSION.SdkInt < BuildVersionCodes.O) 
            return;
        var channel = new NotificationChannel(ChannelId, 
            "AppName default", NotificationImportance.High);
        
        channel.EnableVibration(true); 
        channel.LockscreenVisibility = NotificationVisibility.Public;
        
        var notificationManager = (NotificationManager) context
            .GetSystemService(Context.NotificationService);
        
        notificationManager.CreateNotificationChannel(channel); 
    }
    
    // method extension to ease the creation of the nofication 
    public static NotificationCompat.Builder SetChannelIdIfNeeded( 
        this NotificationCompat.Builder builder, string channelId) 
    { 
        if(Build.VERSION.SdkInt >= BuildVersionCodes.O) 
            builder.SetChannelId(channelId);
    
        return builder; 
    } 
}
```

It's a good idea to create the default channel at the app start, either on your main activity or your custom Application `OnCreate()` override:

```csharp
public override void OnCreate() 
{ 
    base.OnCreate(); 
    NotificationHelper.CreateDefaultChannel(this); 
}
```

Last, but not least, you need to make and slight modification to the code that creates the notification.

Before:

```csharp
var notificationBuilder = new NotificationCompat.Builder(this)
    .SetSmallIcon(Resource.Drawable.ic_notification)
    .SetContentTitle(title)
    .SetContentText(message)
    .SetAutoCancel(true)
    .SetContentIntent(pendingIntent);
```

After:

```csharp
var notificationBuilder = new NotificationCompat.Builder(this)
    .SetChannelIdIfNeeded(NotificationHelper.ChannelId) // method extension
    .SetSmallIcon (Resource.Drawable.ic_notification)
    .SetContentTitle(title)
    .SetContentText(message)
    .SetAutoCancel(true)
    .SetContentIntent(pendingIntent);
```

From now on your push notifications will start working again on Android 8.