Enable access for token refresh

.swiftpm/xcode/xcshareddata/xcschemes/Twift.xcscheme

@@ -40,8 +40,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      shouldUseLaunchSchemeArgsEnv = "NO"
-      codeCoverageEnabled = "YES">
+      shouldUseLaunchSchemeArgsEnv = "NO">
       <EnvironmentVariables>
          <EnvironmentVariable
             key = "ENVIRONMENT"
@@ -72,13 +71,6 @@
       debugDocumentVersioning = "YES"
       debugServiceExtension = "internal"
       allowLocationSimulation = "YES">
-      <EnvironmentVariables>
-         <EnvironmentVariable
-            key = "ENVIRONMENT"
-            value = "PRODUCTION"
-            isEnabled = "YES">
-         </EnvironmentVariable>
-      </EnvironmentVariables>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"

README.md

@@ -18,10 +18,10 @@ New `Twift` instances must be initiated with either OAuth 2.0 user authenticatio
 ```swift
 // OAuth 2.0 User Authentication
 let oauthUser: OAuth2User = OAUTH2_USER
-let userAuthenticatedClient = Twift(.oauth2UserAuth(oauthUser: oauthUser)
+let userAuthenticatedClient = Twift(oauth2User: oauthUser, onTokenRefresh: saveUserCredentials)
 
 // App-Only Bearer Token
-let appOnlyClient = Twift(.appOnly(bearerToken: BEARER_TOKEN)
+let appOnlyClient = Twift(appOnlyBearerToken: BEARER_TOKEN)
 ```
 
 You can authenticate users with `Twift.Authentication().authenticateUser()`:
@@ -36,12 +36,11 @@ do {
     scope: Set(OAuth2Scope.allCases)
   )
 
-  client = Twift(.oauth2UserAuth(oauthUser))
+  client = Twift(oauth2User: oauthUser, onTokenRefresh: saveUserCredentials)
 
   // It's recommended that you store your user auth tokens via Keychain or another secure storage method.
   // OAuth2User can be encoded to a data object for storage and later retrieval.
-  let encoded = try? JSONEncoder().encode(oauthUser))
-  saveUserAuthExample(encoded) // Saves the data to Keychain, for example
+  saveUserCredentials(oauthUser) // Saves the data to Keychain, for example
 } catch {
   print(error.localizedDescription)
 }

Sources/Twift+API.swift

@@ -12,7 +12,7 @@ extension Twift {
                                  body: Data? = nil,
                                  expectedReturnType: T.Type
   ) async throws -> T {
-    if case AuthenticationType.oauth2UserAuth(_) = self.authenticationType {
+    if case AuthenticationType.oauth2UserAuth(_, _) = self.authenticationType {
       try await self.refreshOAuth2AccessToken()
     }
 
@@ -84,7 +84,7 @@ extension Twift {
         consumerCredentials: clientCredentials,
         userCredentials: userCredentials
       )
-    case .oauth2UserAuth(let oauthUser):
+    case .oauth2UserAuth(let oauthUser, _):
       request.addValue("Bearer \(oauthUser.accessToken)", forHTTPHeaderField: "Authorization")
     }
 

Sources/Twift+Authentication.swift

@@ -19,7 +19,7 @@ extension Twift {
     /// OAuth 2.0 User Context authentication.
     ///
     /// When this authentication method is used, the `oauth2User` access token may be automatically refreshed by the client if it has expired.
-    case oauth2UserAuth(_ oauth2User: OAuth2User)
+    case oauth2UserAuth(_ oauth2User: OAuth2User, onRefresh: ((OAuth2User) -> Void)?)
 
     /// App-only authentication
     case appOnly(bearerToken: String)

Sources/Twift.swift

@@ -5,6 +5,14 @@ import Combine
 public class Twift: NSObject, ObservableObject {
   /// The type of authentication access for this Twift instance
   public private(set) var authenticationType: AuthenticationType
+  public var oauthUser: OAuth2User? {
+    switch authenticationType {
+      case .oauth2UserAuth(let user, _):
+        return user
+      default:
+        return nil
+    }
+  }
 
   internal let decoder: JSONDecoder
   internal let encoder: JSONEncoder
@@ -17,6 +25,22 @@ public class Twift: NSObject, ObservableObject {
     self.encoder = Self.initializeEncoder()
   }
 
+  /// Initialises an instance with OAuth2 User authentication
+  /// - Parameters:
+  ///   - oauth2User: The OAuth2 User object for authenticating requests on behalf of a user
+  ///   - onTokenRefresh: A callback invoked when the access token is refreshed by Twift. Useful for storing updated credentials.
+  public convenience init(oauth2User: OAuth2User,
+                          onTokenRefresh: @escaping (OAuth2User) -> Void = { _ in }) {
+    self.init(.oauth2UserAuth(oauth2User, onRefresh: onTokenRefresh))
+  }
+
+  /// Initialises an instance with App-Only Bearer Token authentication
+  /// - Parameters:
+  ///   - appOnlyBearerToken: The App-Only Bearer Token issued by Twitter for authenticating requests
+  public convenience init(appOnlyBearerToken: String) {
+    self.init(.appOnly(bearerToken: appOnlyBearerToken))
+  }
+
   /// Swift's native implementation of ISO 8601 date decoding defaults to a format that doesn't include milliseconds, causing decoding errors because of Twitter's date format.
   /// This function returns a decoder which can decode Twitter's date formats, as well as converting keys from snake_case to camelCase.
   static internal func initializeDecoder() -> JSONDecoder {
@@ -71,9 +95,10 @@ public class Twift: NSObject, ObservableObject {
   }
 
   /// Refreshes the OAuth 2.0 token, optionally forcing a refresh even if the token is still valid
+  /// After a successful refresh, a user-defined callback is performed. (optional)
   /// - Parameter onlyIfExpired: Set to false to force the token to refresh even if it hasn't yet expired.
   public func refreshOAuth2AccessToken(onlyIfExpired: Bool = true) async throws {
-    guard case AuthenticationType.oauth2UserAuth(let oauthUser) = self.authenticationType else {
+    guard case AuthenticationType.oauth2UserAuth(let oauthUser, let refreshCompletion) = self.authenticationType else {
       throw TwiftError.WrongAuthenticationType(needs: .oauth2UserAuth)
     }
 
@@ -106,6 +131,10 @@ public class Twift: NSObject, ObservableObject {
     var refreshedOAuthUser = try JSONDecoder().decode(OAuth2User.self, from: data)
     refreshedOAuthUser.clientId = clientId
 
-    self.authenticationType = .oauth2UserAuth(refreshedOAuthUser)
+    if let refreshCompletion = refreshCompletion {
+      refreshCompletion(refreshedOAuthUser)
+    }
+
+    self.authenticationType = .oauth2UserAuth(refreshedOAuthUser, onRefresh: refreshCompletion)
   }
 }

Tests/TwiftTests/TwiftTests.swift

@@ -4,7 +4,7 @@ import XCTest
 @MainActor
 final class TwiftTests {
   static var userAuthClient: Twift {
-    Twift(.oauth2UserAuth(OAuth2User(accessToken: "test", refreshToken: "test_refresh", scope: Set(OAuth2Scope.allCases))))
+    Twift(.oauth2UserAuth(OAuth2User(accessToken: "test", refreshToken: "test_refresh", scope: Set(OAuth2Scope.allCases)), onRefresh: { _ in }))
   }
 
   static var appOnlyClient: Twift {