Support getting a Swap Token

README.md

@@ -148,14 +148,42 @@ Have a look [in the example](example/lib/main.dart) for detailed insights on how
 
 You can optionally specify "token swap" URLs to manage tokens with a backend service that protects your OAuth client secret. For more information refer to the [Spotify Token Swap and Refresh Guide](https://developer.spotify.com/documentation/ios/guides/token-swap-and-refresh/)
 
+#### Web setup
+
 ```dart
 SpotifySdkPlugin.tokenSwapURL = 'https://example.com/api/spotify/token';
 SpotifySdkPlugin.tokenRefreshURL = 'https://example.com/api/spotify/refresh';
 ````
 
 On web, this package will perform an Authorization Code (without PKCE) flow, then exchange the code and refresh the token with a backend service you run at the URLs provided.
 
-Token Swap is for now "web only". While the iOS SDK also supports the "token swap", this flow is not yet supported.
+#### Mobile setup
+
+* Note: Mobile implementation currently is only for getting the Swap token to exchange for a real token. It will not authenticate the SpotifySdk's other functions.
+
+For iOS setup: Add a `SpotifySDKCallbackURL` and `LSApplicationQueriesSchemes` to your Info.plist file. This allows the SDK to search for the Spotify app and launch your app after receiving authentication from the Spotify app.
+
+```swift
+  <key>LSApplicationQueriesSchemes</key>
+    <array>
+      <string>spotify</string>
+  </array>
+  <key>SpotifySDKCallbackURL</key>
+  <string>example://auth/callback</string>
+```
+
+Dart code:
+
+```dart
+SpotifySdk.getSwapToken(
+  clientId: "",
+  redirectUri: "example://auth/spotify/callback",
+  scopes: "app-remote-control,user-modify-playback-state,playlist-read-private",
+  tokenSwapUrl: "https://example.com/api/spotify/swap",
+);
+```
+
+Check the [Spotify docs](https://developer.spotify.com/documentation/ios/concepts/token-swap-and-refresh) for how to setup the tokenSwapUrl.
 
 ### Api
 
@@ -164,6 +192,7 @@ Token Swap is for now "web only". While the iOS SDK also supports the "token swa
 | Function  | Description| Android | iOS | Web |
 |---|---|---|---|---|
 | connectToSpotifyRemote  | Connects the App to Spotify | ✔ | ✔ | ✔ |
+| getSwapToken  | Get's the Swap Token from the Spotify app | ✔ | ✔ | ❌ |
 |  getAccessToken | Gets the Access Token that you can use to work with the [Web Api](https://developer.spotify.com/documentation/web-api/) | ✔ |  ✔ | ✔ |
 |  disconnect | Disconnects the app connection | ✔ |  ✔ | ✔ |
 |  subscribeConnectionStatus | Subscribes to the current player state. | ✔ |  ✔ | 🚧 |

android/build.gradle

@@ -59,7 +59,7 @@ android {
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     // -- spotify
-    implementation "com.spotify.android:auth:2.1.0"
+    implementation "com.spotify.android:auth:2.1.2"
     implementation project(':spotify-app-remote')
     implementation 'com.google.code.gson:gson:2.10.1'
     // -- events

android/src/main/AndroidManifest.xml

@@ -1,5 +1,17 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <application>
+        <!-- Spotify SDK Authentication Activities -->
+        <activity
+            android:exported="true"
+            android:name="com.spotify.sdk.android.authentication.AuthCallbackActivity"
+            android:theme="@android:style/Theme.Translucent.NoTitleBar">
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+            </intent-filter>
+        </activity>
+
         <activity
             android:name="com.spotify.sdk.android.authentication.LoginActivity"
             android:theme="@android:style/Theme.Translucent.NoTitleBar" />

android/src/main/kotlin/de/minimalme/spotify_sdk/SpotifySdkPlugin.kt

@@ -4,13 +4,13 @@ import android.app.Activity
 import android.content.Context
 import android.content.Intent
 import android.util.Log
+import android.content.pm.PackageManager
+import android.webkit.URLUtil
 import com.spotify.android.appremote.api.ConnectionParams
 import com.spotify.android.appremote.api.Connector.ConnectionListener
 import com.spotify.android.appremote.api.SpotifyAppRemote
 import com.spotify.android.appremote.api.error.*
-import com.spotify.sdk.android.auth.AuthorizationClient
-import com.spotify.sdk.android.auth.AuthorizationRequest
-import com.spotify.sdk.android.auth.AuthorizationResponse
+import com.spotify.sdk.android.auth.*
 import de.minimalme.spotify_sdk.subscriptions.*
 import io.flutter.embedding.engine.plugins.FlutterPlugin
 import io.flutter.embedding.engine.plugins.activity.ActivityAware
@@ -35,6 +35,8 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
     private val channelName = "spotify_sdk"
     private val loggingTag = "spotify_sdk"
 
+    private val REQUEST_SWAP_CODE = 1337
+
     // event channels
     private var playerContextChannel : EventChannel? = null
     private var playerStateChannel : EventChannel? = null
@@ -50,8 +52,10 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
 
     //connecting
     private val methodConnectToSpotify = "connectToSpotify"
+    private val methodGetSwapToken = "getSwapToken"
     private val methodGetAccessToken = "getAccessToken"
     private val methodDisconnectFromSpotify = "disconnectFromSpotify"
+    private val methodIsSpotifyInstalled = "isSpotifyInstalled"
 
     // connectApi
     private val methodSwitchToLocalDevice = "switchToLocalDevice"
@@ -86,6 +90,8 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
     private val paramClientId = "clientId"
     private val paramRedirectUrl = "redirectUrl"
     private val paramScope = "scope"
+    private val paramScopes = "scopes"
+    private val paramTokenSwapUrl = "tokenSwapUrl"
     private val paramSpotifyUri = "spotifyUri"
     private val paramImageUri = "imageUri"
     private val paramImageDimension = "imageDimension"
@@ -175,8 +181,10 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
         when (call.method) {
             //connecting to spotify
             methodConnectToSpotify -> connectToSpotify(call.argument(paramClientId), call.argument(paramRedirectUrl), result)
+            methodGetSwapToken -> getSwapToken(call.argument(paramClientId), call.argument(paramRedirectUrl), call.argument(paramScopes), call.argument(paramTokenSwapUrl), result)
             methodGetAccessToken -> getAccessToken(call.argument(paramClientId), call.argument(paramRedirectUrl), call.argument(paramScope), result)
             methodDisconnectFromSpotify -> disconnectFromSpotify(result)
+            methodIsSpotifyInstalled -> isSpotifyInstalled(result)
             //connectApi calls
             methodSwitchToLocalDevice -> spotifyConnectApi?.switchToLocalDevice()
             //playerApi calls
@@ -204,6 +212,7 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
             //imageApi calls
             methodGetImage -> spotifyImagesApi?.getImage(call.argument(paramImageUri), call.argument(paramImageDimension))
             // method call is not implemented yet
+
             else -> result.notImplemented()
         }
     }
@@ -305,6 +314,64 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
         }
     }
 
+    /**
+     * Gets a swap token from Spotify using token swap authentication.
+     * 
+     * @param clientId The Spotify client ID
+     * @param redirectUrl The redirect URL registered in Spotify dashboard
+     * @param scopes Comma-separated list of Spotify authorization scopes
+     * @param tokenSwapUrl URL for token swap endpoint
+     * @param result Flutter result callback
+     */
+    private fun getSwapToken(
+        clientId: String?,
+        redirectUrl: String?,
+        scopes: String?,
+        tokenSwapUrl: String?,
+        result: Result
+    ) {
+        try {
+            // Validate required parameters
+            when {
+                clientId.isNullOrBlank() -> throw IllegalArgumentException("Client ID is required")
+                redirectUrl.isNullOrBlank() -> throw IllegalArgumentException("Redirect URL is required")
+                scopes.isNullOrBlank() -> throw IllegalArgumentException("Scopes are required")
+                tokenSwapUrl.isNullOrBlank() -> throw IllegalArgumentException("Token swap URL is required")
+                !URLUtil.isValidUrl(tokenSwapUrl) -> throw IllegalArgumentException("Invalid token swap URL")
+            }
+
+            // Check Spotify installation
+            if (!_isSpotifyInstalled()) {
+                result.error("SPOTIFY_NOT_INSTALLED", "Spotify is not installed", null)
+                return
+            }
+
+            // Verify activity exists
+            val activity = applicationActivity ?: run {
+                result.error("NO_ACTIVITY", "Activity is not attached", null)
+                return
+            }
+
+            // Store pending operation
+            methodGetSwapToken.checkAndSetPendingOperation(result)
+
+            // Build authorization request
+            val request = AuthorizationRequest.Builder(
+                clientId,
+                AuthorizationResponse.Type.CODE,
+                redirectUrl
+            ).apply {
+                setScopes(scopes.split(",").toTypedArray())
+                setShowDialog(true)
+            }.build()
+
+            // Start authentication
+            AuthorizationClient.openLoginActivity(activity, REQUEST_SWAP_CODE, request)
+        } catch (e: Exception) {
+            result.error("AUTH_ERROR", e.message, e.toString())
+        }
+    }
+
     private fun getAccessToken(clientId: String?, redirectUrl: String?, scope: String?, result: Result) {
         if (applicationActivity == null) {
             throw IllegalStateException("getAccessToken needs a foreground activity")
@@ -363,6 +430,9 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
             AuthorizationResponse.Type.TOKEN -> {
                 result.success(response.accessToken)
             }
+            AuthorizationResponse.Type.CODE -> {
+                result.success(response.code)
+            }
             AuthorizationResponse.Type.ERROR -> result.error(errorAuthenticationToken, "Authentication went wrong", response.error)
             else -> result.notImplemented()
         }
@@ -376,6 +446,38 @@ class SpotifySdkPlugin : MethodCallHandler, FlutterPlugin, ActivityAware, Plugin
         }
         pendingOperation = PendingOperation(this, result)
     }
+
+    private fun isSpotifyInstalled(result: Result) {
+        try {
+            if (applicationActivity == null) {
+                result.error(
+                    "NO_ACTIVITY", 
+                    "Activity is not attached", 
+                    null
+                )
+                return
+            }
+
+            val isInstalled = _isSpotifyInstalled()
+
+            result.success(isInstalled)
+        } catch (e: Exception) {
+            result.error(
+                "SPOTIFY_CHECK_FAILED",
+                "Failed to check if Spotify is installed",
+                e.toString()
+            )
+        }
+    }
+
+    private fun _isSpotifyInstalled(): Boolean {
+        return try {
+            applicationActivity!!.packageManager.getPackageInfo("com.spotify.music", 0)
+            true
+        } catch (e: PackageManager.NameNotFoundException) {
+            false
+        }
+    }
 }
 
 private class PendingOperation internal constructor(val method: String, val result: Result)

ios/Classes/SpotifySdkConstants.swift

@@ -4,6 +4,7 @@ public class SpotifySdkConstants
 {
     //connecting
     public static let methodConnectToSpotify = "connectToSpotify"
+    public static let methodGetSwapToken = "getSwapToken"
     public static let methodGetAccessToken = "getAccessToken"
     public static let methodDisconnectFromSpotify = "disconnectFromSpotify"
 
@@ -31,6 +32,7 @@ public class SpotifySdkConstants
 
     public static let paramClientId = "clientId"
     public static let paramRedirectUrl = "redirectUrl"
+    public static let paramTokenSwapUrl = "tokenSwapUrl"
     public static let paramSpotifyUri = "spotifyUri"
     public static let paramAsRadio = "asRadio"
     public static let paramImageUri = "imageUri"
@@ -42,5 +44,8 @@ public class SpotifySdkConstants
     public static let paramRepeatMode = "repeatMode"
     public static let paramTrackIndex = "trackIndex"
     public static let scope = "scope"
+    public static let paramScopes = "scopes"
     public static let getLibraryState = "getLibraryState"
+
+    public static let methodIsSpotifyInstalled = "isSpotifyInstalled"
 }

ios/Classes/SwiftAppDelegate.swift

@@ -0,0 +1,32 @@
+import Flutter
+import UIKit
+
+public class SpotifyAppDelegate {
+    public static func application(
+        _ application: UIApplication,
+        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+    ) {
+        // Initialize Spotify-specific components
+        if let registrar = (application.delegate as? FlutterAppDelegate)?.registrar(
+            forPlugin: "SwiftSpotifySdkPlugin")
+        {
+            SwiftSpotifySdkPlugin.register(with: registrar)
+        }
+    }
+
+    public static func application(
+        _ app: UIApplication,
+        open url: URL,
+        options: [UIApplication.OpenURLOptionsKey: Any] = [:]
+    ) -> Bool {
+        // Handle Spotify URL callback
+        if let value = Bundle.main.infoDictionary?["SpotifySDKCallbackURL"] as? String {
+            if url.absoluteString.contains(value) {
+                SwiftSpotifySdkPlugin.shared.handleSpotifyCallback(url: url)
+                return true
+            }
+        }
+
+        return false
+    }
+}