Publishing to Google Play
Although there are many app markets for distributing an application, Google Play is arguably the largest and most visited store in the world for Android apps. Google Play provides a single platform for distributing, advertising, selling, and analyzing the sales of an Android application.
This section will cover topics that are specific to Google Play, such as registering to become a publisher, gathering assets to help Google Play promote and advertise your application, guidelines for rating your application on Google Play, and using filters to restrict the deployment of an application to certain devices.
To distribute an application through Google Play, a developer account must be created. This only needs to be performed once, and does involve a one time fee of $25 USD.
All applications need to be signed with a cryptographic key that expires after October 22, 2033.
The maximum size for an APK published on Google Play is 100MB. If an application exceeds that size, Google Play will allow extra assets to be delivered through APK Expansion Files. Android Expansion files permit the APK to have 2 additional files, each of them up to 2GB in size. Google Play will host and distribute these files at no cost. Expansion files will be discussed in another section.
Google Play is not globally available. Some locations may not be supported for the distribution of applications.
Becoming a Publisher
To publish applications on Google play, it is necessary to have a publisher account. To sign up for a publisher account follow these steps:
- Visit the Google Play Developer Console.
- Enter basic information about your developer identity.
- Read and accept the Developer Distribution Agreement for your locale.
- Pay the $25 USD registration fee.
- Confirm verification by e-mail.
- After the account has been created, it is possible to publish applications using Google Play.
Google Play does not support all countries/regions in the world. The most up-to-date lists of countries/regions can be found in the following links:
Supported Locations for Developer & Merchant Registration – This is a list of all countries/regions where developers may register as merchants and sell paid applications.
Supported Locations for distribution to Google Play users – This is a list of all countries/regions where applications may be distributed.
Preparing Promotional Assets
To effectively promote and advertise an application on Google Play, Google allows developers to submit promotional assets such as screenshots, graphics, and video to be submitted. Google Play will then use those assets to advertise and promote the application.
A launcher icon is a graphic that represents an application. Each launcher icon should be a 32-bit PNG with an alpha channel for transparency. An application should have icons for all of the generalized screen densities as outlined in the list below:
- ldpi (120dpi) – 36 x 36 px
- mdpi (160dpi) – 48 x 48 px
- hdpi (240dpi) – 72 x 72 px
- xhdpi (320dpi) – 96 x 96 px
Launcher icons are the first things that a user will see of applications on Google Play, so care should be taken to make the launcher icons visually appealing and meaningful.
Tips for Launcher Icons:
Simple and uncluttered– Launcher icons should be kept simple and uncluttered. This means excluding the name of the application from the icon. Simpler icons will be more memorable, and will be easier to distinguish at the smaller sizes.
Icons should not be thin– Overly thin icons will not stand out well on all backgrounds.
Use the alpha channel– Icons should make use of the alpha channel, and should not be full-framed images.
High Resolution Application Icons
Applications on Google Play require a high fidelity version of the application icon. It is only used by Google Play, and does not replace the application launcher icon. The specifications for the high-resolution icon are:
- 32-bit PNG with an alpha channel
- 512 x 512 pixels
- Maximum size of 1024KB
The Android Asset Studio is a helpful tool for creating suitable launcher icons and the high-resolution application icon.
Google play requires a minimum of two and a maximum of eight screenshots for an application. They will be displayed on an application's details page in Google Play.
The specs for screenshots are:
- 24 bit PNG or JPG with no alpha channel
- 320w x 480h or 480w x 800h or 480w x 854h. Landscaped images will be cropped.
This is an optional image used by Google Play:
- It is a 180w x 120h 24 bit PNG or JPG with no alpha channel.
- No border in art.
Used by the featured section of Google Play. This graphic may be displayed alone without an application icon.
- 1024w x 500h PNG or JPG with no alpha channel and no transparency.
- All of the important content should be within a frame of 924x500. Pixels outside of this frame may be cropped for stylistic purposes.
- This graphic may be scaled down: use large text and keep graphics simple.
This is a URL to a YouTube video showcasing the application. The video should be 30 seconds to 2 minutes in length and showcase the best parts of your application.
Publishing to Google Play
Xamarin Android 7.0 introduces an integrated workflow for publishing apps to Google Play from Visual Studio. If you are using a version of Xamarin Android earlier than 7.0, you must manually upload your APK via the Google Play Developer Console. Also, you must have at least one APK already uploaded before you can use the integrated workflow. If you have not yet uploaded your first APK, you must upload it manually. For more information, see Manually Uploading the APK.
Creating a New Certificate, explained how to create a new certificate for signing Android apps. The next step is to publish a signed app to Google Play:
- Sign into your Google Play Developer account to create a new project that is linked to your Google Play Developer account.
- Create an OAuth Client that authenticates your app.
- Enter the resulting Client ID and Client secret into Visual Studio.
- Register your account with Visual Studio.
- Sign the app with your certificate.
- Publish your signed app to Google Play.
In Archive for Publishing, the Distribution Channel dialog presented two choices for distribution: Ad Hoc and Google Play. If the Signing Identity dialog is displayed instead, click Back to return to the Distribution Channel dialog. Select Google Play:
In the Signing Identity dialog, select the identity created in Creating a New Certificate and click Continue:
In the Google Play Accounts dialog, click the + button to add a new Google Play Account:
In the Register Google API Access dialog, you must provide the Client ID and Client secret that provides API access to your Google Play Developer account:
The next section explains how to create a new Google API project and generate the needed Client ID and Client secret.
Create a Google API Project
First, sign into your Google Play Developer account. If you do not already have a Google Play Developer account, see Get Started with Publishing. Also, the Google Play Developer API Getting Started explains how to use the Google Play Developer API. After you sign into the Google Play Developer Console, click CREATE APPLICATION:
After creating the new project, it will be linked to your Google Play Developer Console account.
The next step is to create an OAuth Client for the app (if one has not already been created). When users request access to their private data using your app, your OAuth Client ID is used to authenticate your app.
Go to the Settings page.
In the Settings page, select API access and click CREATE OAUTH CLIENT to create a new OAuth client:
After a few seconds, a new Client ID is generated. Click View in Google Developers Console to see your new Client ID in the Google Developer's Console:
The Client ID is displayed along its name and creation date. Click the Edit OAuth Client icon to view the Client secret for your app:
The default name of the OAuth client is Google Play Android Developer. This can be changed to the name of Xamarin.Android app, or any suitable name. In this example, the OAuth Client name is changed to the name of the app, MyApp:
Click Save to save changes. This returns to the Credentials page where to download the credentials by clicking on the Download JSON icon:
This JSON file contains the Client ID and Client secret that you can cut and paste into the Sign and Distribute dialog in the next step.
Register Google API Access
Use the Client ID and Client secret to complete the Google Play API Account dialog in Visual Studio. It is possible to give the account a description – this makes it possible to register more than one Google Play account and upload future APK's to different Google Play accounts. Copy the Client ID and Client secret to this dialog and click Register:
A web browser will open and prompt you to sign into your Google Play Android Developer account (if you are not already signed in). After you sign in, the following prompt is displayed in the web browser. Click Allow to authorize the app:
After clicking Allow, the browser reports Received verification code. Closing... and the app is added to the list of Google Play Accounts in Visual Studio. In the Google Play Accounts dialog, click Continue:
Next, the Google Play Track dialog is presented. Google Play offers five possible tracks for uploading your app:
- Internal – Used for quickly distributing your app for internal testing and quality assurance checks.
- Alpha – Used for uploading an early version of your app to a small list of testers.
- Beta – Used for uploading an early version of your app to a larger list of testers.
- Production – Used for full distribution to the Google Play store.
- Custom – Used for testing pre-release versions of your app with specific users by creating a list of testers by email address.
Choose which Google Play track will be used for uploading the app and click Upload.
For more information about Google Play testing, see Set up open/closed/internal tests.
Next, a dialog is presented to enter the password for the signing certificate. Enter the password and click OK:
The Archive Manager displays the progress of the upload:
When the upload finishes, completion status is shown in the lower left hand corner of Visual Studio:
If you do not see your custom track when selecting a Google Play track, make sure you have created a release for that track on the Google Play Developer Console. For instructions on how to create a release, see Prepare & roll out releases.
Note that one APK must have already been submitted to the Google Play store before the Publish to Google Play will work. If an APK is not already uploaded the Publishing Wizard will display the following error in the Errors pane:
When this error occurs, manually upload an APK (such as an Ad Hoc build) via the Google Play Developer Console and use the Distribution Channel dialog for subsequent APK updates. For more information, see Manually Uploading the APK. The version code of the APK must change with each upload, otherwise the following error will occur:
To resolve this error, rebuild the app with a different version number and resubmit it to Google Play via the Distribution Channel dialog.