AppAuth with IdentityServer 4 for android

You can now use the AppAuth library with WebView check this

Android sample using AppAuth-Android with IdentityServer4

Identity Server on the backend

new Client
{
    	ClientId = _configuration["Clients:Mobile:Id"],
 	ClientName = "Mobile Application",
        ClientSecrets = { new Secret(_configuration["Clients:Mobile:Secret"].Sha256())},
        RedirectUris = {_configuration["Clients:Mobile:RedirectUrl"]},
        PostLogoutRedirectUris = { _configuration["Clients:Mobile:PostLogoutRedirectUrl"] },
	
        AllowedGrantTypes = GrantTypes.Code,
        AllowAccessTokensViaBrowser = true,
        RequireConsent = false,

        AllowOfflineAccess = true,
        RefreshTokenUsage = TokenUsage.ReUse,

        AllowedScopes = {
             IdentityServerConstants.StandardScopes.OpenId,
             IdentityServerConstants.StandardScopes.Profile
           }
  }

Edit the data in the gradle.properties file

clientId= "myClientId"
clientSecret= "myClientSecret"
redirectUri= "myRedirectUri://callback"
scope= "openid offline_access"
authorizationEndpointUri= "myAuthorizationEndpointUri"
tokenEndpointUri= "myTokenEndPointUri"
registrationEndpointUri= "myRegistrationEndPointUri"
responseType= "code"

Add the redirect uri to gradle.app :

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.3"
    defaultConfig {
       ...
        manifestPlaceholders = [
                'appAuthRedirectScheme': 'myRedirectUri' //Without ://callback
        ]
    }
}

Add the redirect uri to the RedirectUriReceiverActivity in manifest :

<activity
	android:name="net.openid.appauth.RedirectUriReceiverActivity"
	android:theme="@style/Theme.AppCompat.NoActionBar">
		<intent-filter>
			<action android:name="android.intent.action.VIEW"/>

			<category android:name="android.intent.category.DEFAULT"/>
			<category android:name="android.intent.category.BROWSABLE"/>

			<data android:scheme="myRedirectUri"/>
		</intent-filter>
</activity>