Standalone Wear apps

A Wear OS app can work independently of a phone. Users can complete tasks on a watch, without access to an Android or iOS phone.

Plan your apps

You can use the multiple APK (multi-APK) feature of Google Play to publish more than one APK under the same application listing. A watch APK should be distributed using that feature; do not embed a watch APK in a phone APK. For information about setting up your app for distribution through the Google Play Store, see Packaging and Distributing Wear Apps and How Multiple APKs Work.

Note: To qualify for promotion in the Google Play Store on Wear (that is, in the on-watch Play Store), your app needs to function independently from a phone. iOS as well as Android support is required.

Generally, the minimum and target API level for a standalone app, and for Wear 2.0, is level 25. The minimum SDK level can be 23 only if you are using the same APK for Wear 1.0 and 2.0 (and thus have an embedded Wear 1.0 APK).

Caution: If you publish an update to your existing, production phone APK that has removed an embedded Wear APK, production users who update the phone APK before installing your standalone Wear APK will lose their existing Wear app and its data. If you publish an update to your existing, production phone APK, continue to embed your watch APK into that phone APK.

Run-time permissions are required for standalone apps.

For information about network requests and high-bandwidth network access, see Network Access and Syncing.

Identify an app as standalone

Wear apps must have a meta-data element in the Android Manifest file, as a child of the <application> element. The name of the meta-data element is com.google.android.wearable.standalone and the value must be true or false. The element indicates whether your watch app is a standalone app and thus doesn't require a phone-side Android app to operate. If the setting for the element is true, your app can be made available in the Play Store on watches paired to iPhones, as long as your active APKs in all channels (e.g., in the beta channel) have the element set to true. If not all of your APKs (alpha, beta, and production) that currently are served to users have the above setting, your app will be unavailable when a user searches on a watch paired to an iPhone.

A watch app can be considered as one of the following:

• Completely independent of a phone app
• Semi-independent (a phone app is not required and would provide only optional features)
• Dependent on a phone app

If a watch app is completely independent or semi-independent, it is considered to be in the standalone category. You must indicate this categorization to the Google Play store by setting the value of this meta-data element to true:

<application>
...
  <meta-data
    android:name="com.google.android.wearable.standalone"
    android:value="true" />
...
</application>

Since a standalone app (that is, an independent or semi-independent app) can be installed by an iPhone user or a user of an Android phone that lacks the Play Store, the watch app should be usable without the phone app.

If a watch app depends on a phone app, set the value of the above meta-data element to false. Setting the element to false signifies that the watch app should be installed only on a watch that is paired with a phone that has the Play Store.

Note: Even if the value is false, the watch app can be installed before the phone app is installed. Therefore, if a watch app detects that a companion phone lacks a necessary phone app, the watch app should prompt the user to install the phone app.

Define an app as a Wear app

You must ensure the <uses-feature> tag is defined in the Android Manifest file in your app. It must indicate that it is a watch app, for example, android:name="android.hardware.type.watch" as follows:

<manifest>
...
  <uses-feature android:name="android.hardware.type.watch" />
...
</manifest>

Shared code and data storage

Code can be shared between a Wear app and a phone app. Optionally, code that is specific to a form factor can be in a separate module.

For example, common code for networking can be in a shared library.

You can use standard Android storage APIs to store data locally, as you would on a phone. For example, you can use the SharedPreferences APIs or the Room persistence library.

Detect your app on another device

Your watch app can detect if the corresponding phone app is available and vice versa.

Your phone app or watch app can use the CapabilityClient to advertise the app's presence to a paired device. It can do so statically and dynamically. When an app is on a node in a user's Wear network (i.e., on a phone, paired watch, or in the cloud), the CapabilityClient enables another app to detect if it is installed. For more information, see Advertise capabilities.

If one of your apps cannot detect the other, you can enable a user to open the Play Store listing on their remote device. This is a solution for watch apps that require their companion phone app's presence to function properly. A prerequisite is to check for the Play Store's presence on the remote device.

Note that not all phones support the Play Store (such as iPhones, etc.).

This section describes best practices for these scenarios:

• Your standalone watch app needs your phone app
• Your phone app needs your standalone watch app

Please review the sample that shows this functionality. For more information about the classes described below, see the Wear API Reference. Also in that reference is information about the PhoneDeviceType class, which contains a getPhoneDeviceType() method that enables your Wear app to check if a companion phone is an Android or iOS device.

Specify capability names for detecting your apps

For the app corresponding to each device type (watch or phone), specify a unique string for the capability name in the res/values/wear.xml file.

For example, in your mobile module, the wear.xml file could include the following:

<resources>
    <string-array name="android_wear_capabilities">
        <item>verify_remote_example_phone_app</item>
    </string-array>
</resources>

In your wear module, the wear.xml file would include a different value for the capability name, such as the following:

<resources>
    <string-array name="android_wear_capabilities">
        <item>verify_remote_example_wear_app</item>
    </string-array>
</resources>

For more information, see Advertise capabilities.

App detection and opening a URL from a watch

Your watch app can detect if a user's companion phone has your phone app:

1. Use the CapabilityClient to check if your phone app is installed on the paired phone. For more information, see the sample.
2. If your phone app isn't installed on the phone, use the PhoneDeviceType.getPhoneDeviceType() method to check the type of the phone.
3. If PhoneDeviceType.DEVICE_TYPE_ANDROID is returned, the phone is an Android phone. Call RemoteIntent.startRemoteActivity() on the Wear device to open the app store on the phone. Use the market URI for your phone app (which may be different from your phone URI). For example, use a market URI such as: market://details?id=com.example.android.wearable.wear.finddevices
4. If PhoneDeviceType.DEVICE_TYPE_IOS is returned, it means the phone is an iOS phone (with no Play Store available). Open the App Store on the iPhone by calling RemoteIntent.startRemoteActivity() on the Wear device. You can specify your app's iTunes URL, for example, https://itunes.apple.com/us/app/yourappname. On an iPhone, from Wear OS, you cannot programmatically determine if your phone app is installed. As a best practice, provide a mechanism to the user (e.g., a button) to manually trigger the opening of the App Store.

Note that using the RemoteIntent API described above, you can specify that any URL be opened on the phone from the watch, and no phone app is required.

Details for detecting the type of paired phone

Here is a snippet that uses the getPhoneDeviceType() method to check the type of phone to which the watch is paired:

int phoneDeviceType =
PhoneDeviceType.getPhoneDeviceType(context);

The value returned by the getPhoneDeviceType() method is one of the following:

Return value	Description
DEVICE_TYPE_ANDROID	The companion phone is an Android device.
DEVICE_TYPE_IOS	The companion phone is an iOS device.
DEVICE_TYPE_ERROR_UNKNOWN	An error occurred in determining the type of the paired phone; another check should be made later.

App detection starting from an Android phone

Your Android phone can detect if a user's Wear devices have your watch app:

1. Using the NodeClient, find all watches connected to the user's phone. For more information, see the sample.
2. Using the CapabilityClient, check which of the user's watches have your app installed.
3. If your app isn't installed on all of the user's watches (compare the results from Step 1 with the results from Step 2), allow the user to open the Play Store on the remaining Wear devices from the phone via the RemoteIntent.startRemoteActivity() method. Specifically, use the market URI for the Wear app (which may be different from your phone app's URI). For example, use a market URI such as: market://details?id=com.example.android.wearable.wear.finddevices

Location data for watches paired to iPhones

For watches paired to iPhones, developers should use the Fused Location Provider (FLP) to get location data on a watch. See Detecting location on Wear.

If the companion phone is available, FLP uses the companion phone for location data.

Obtain only the necessary data

Generally, when obtaining data from the internet, you should get only the necessary data. Otherwise, you may introduce unnecessary latency, memory use, and battery use.

When a watch is connected over a Bluetooth LE connection, your app may have access to a bandwidth of only 4 kilobytes per second, depending on the watch. Therefore, the following steps are recommended:

• Audit your network requests and responses for extra data that only is for a phone app
• Shrink large images before you send them over a network to a watch

For cases where a high-bandwidth network is needed, see High-bandwidth network access.

Additional code samples

The Android WearVerifyRemoteApp and Android SpeedTracker samples further demonstrate the use of the APIs covered on this page.