FacebookSDK(4.1.x) Custom Login UI Button - Swift(1.2)

Question

Following this tutorial, I have managed to make a Facebook Login Button working. However, it is assigning the button image automatically from the SDK and it is not customisa

Answer 1

Reusable class (Swift 4).

Usage: FacebookSignIn.shared.signIn(from: yourVC, completion: yourCompletion)

class FacebookSignIn {

   enum Error: Swift.Error {
      case unableToInitializeGraphRequest
      case unexpectedGraphResponse
      case permissionsIsNotGranted
      case unexpectedLoginResponse
      case canceled
   }

   struct Permissions {

      static let email = "email"
      static let profile = "public_profile"

      static func isValidPermissions(_ permissions: Set) -> Bool {
         return permissions.contains(email) && permissions.contains(profile)
      }

      static var permissions: [String] {
         return [email, profile]
      }
   }

   public static let shared = FacebookSignIn()

   private init() {
   }

}

extension FacebookSignIn {

   func signIn(from: UIViewController, completion: Result.Completion?) {
      let manager = FBSDKLoginManager()
      manager.loginBehavior = .native
      if !isValidToken {
         manager.logOut()
      }
      if let token = FBSDKAccessToken.current() {
         let interval = token.expirationDate.timeIntervalSince(Date())
         if interval > 300 { // At least 5 min token will be valid
            performLogin {
               switch $0 {
               case .failure(let error):
                  completion?(.failure(error))
               case .success(let info):
                  completion?(.success(SignInResponse(accessToken: token.tokenString, userInfo: info)))
               }
            }
         } else {
            FBSDKAccessToken.refreshCurrentAccessToken { [weak self] _, _, error in
               if let error = error {
                  manager.logOut()
                  completion?(.failure(error))
               } else {
                  let token = FBSDKAccessToken.current()?.tokenString ?? "" // Should be always valid value at this point.
                  self?.performLogin {
                     switch $0 {
                     case .failure(let error):
                        completion?(.failure(error))
                     case .success(let info):
                        completion?(.success(SignInResponse(accessToken: token, userInfo: info)))
                     }
                  }
               }
            }
         }
      } else {
         manager.logIn(withReadPermissions: Permissions.permissions, from: from) { [weak self] result, error in
            if let error = error {
               manager.logOut()
               completion?(.failure(error))
               return
            }
            guard let result = result else {
               manager.logOut()
               completion?(.failure(Error.unexpectedLoginResponse))
               return
            }
            let permissions = result.grantedPermissions ?? Set()
            let token = result.token?.tokenString ?? "" // Should be always valid value at this point.
            if result.isCancelled {
               manager.logOut()
               completion?(.failure(Error.canceled))
            } else if Permissions.isValidPermissions(permissions) {
               self?.performLogin {
                  switch $0 {
                  case .failure(let error):
                     completion?(.failure(error))
                  case .success(let info):
                     completion?(.success(SignInResponse(accessToken: token, userInfo: info)))
                  }
               }
            } else {
               manager.logOut()
               completion?(.failure(Error.permissionsIsNotGranted))
            }
         }
      }
   }

   private var isValidToken: Bool {
      guard let token = FBSDKAccessToken.current() else {
         return false
      }
      return Permissions.isValidPermissions(token.permissions ?? Set())
   }

   private func makeGraphRequest() -> FBSDKGraphRequest? {
      guard FBSDKAccessToken.current().tokenString != nil else {
         return nil
      }
      // You might not get email: https://developers.facebook.com/docs/facebook-login/permissions/v2.4
      // Note, even if you request the email permission it is not guaranteed you will get an email address. For example,
      // if someone signed up for Facebook with a phone number instead of an email address, the email field may be empty.
      let fields = "email,id,first_name,last_name,gender"
      return FBSDKGraphRequest(graphPath: "me", parameters: ["fields": fields])
   }

   private func performLogin(completion: Result<[String: String]>.Completion?) {
      let manager = FBSDKLoginManager()
      guard let request = makeGraphRequest() else {
         manager.logOut()
         completion?(.failure(Error.unableToInitializeGraphRequest))
         return
      }
      _ = request.start { _, result, error in
         if let e = error {
            manager.logOut()
            completion?(.failure(e))
         } else if let result = result as? [String: String] {
            completion?(.success((result)))
         } else {
            manager.logOut()
            completion?(.failure(Error.unexpectedGraphResponse))
         }
      }
   }

}

---

public struct SignInResponse {

   public let accessToken: String
   public let userInfo: [String: String]

   public init(accessToken: String, userInfo: [String: String]) {
      self.accessToken = accessToken
      self.userInfo = userInfo
   }
}


public enum Result {

   case success(T)
   case failure(Swift.Error)

   public typealias Completion = (Result) -> Void
}