title: Swift 4 - Expression type '@lvalue String?' is ambiguous without more context
body: <p>I'm trying to record a score and Highscore on a game that I'm doing. But I've been getting this error:</p>
  
  <p><a href="https://i.stack.imgur.com/rmcQb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rmcQb.png" alt="enter image description here"></a></p>
  
  <p>Any clues of how can I fix this? I have Xcode 10 and I'm working with Swift 4. Thanks in advance!</p>
  
  <pre><code>import UIKit
  import Foundation
  
  class ScoreVC: UIViewController {
      @IBOutlet weak var scoreLabel: UILabel!
      @IBOutlet weak var highscoreLabel: UILabel!
  
      @IBOutlet weak var reset: UIButton!
      @IBOutlet weak var points: UIButton!
  
      var Score = 0
      var Highscore = 0
  
      override func viewDidLoad() {
          super.viewDidLoad()
  
          let HighscoreDefault = UserDefaults.standard
  
          if (HighscoreDefault.value(forKey: "Highscore") != nil) {
              Highscore = HighscoreDefault.value(forKey: "Highscore") as! Int
              highscoreLabel.text = NSString(format: "Highscore: %i", Highscore) as String
          }
      }
  
      @IBAction func resetButton(_ sender: Any) {
          Score = 0
          scoreLabel.text = NSString(format: "Score: %i", Score) as String
      }
  
      @IBAction func pointsButton(_ sender: Any) {
          Score +=
          scoreLabel.text = NSString(format: "Score: %i", Score) as String
          if (Score &gt; Highscore) {
              Highscore = Score
              highscoreLabel.text = NSString(format: "Highscore: %i", Highscore) as String
  
              var HighscoreDefault = UserDefaults.standard
              HighscoreDefault.setValue(Highscore, forKey: "Highscore")
              HighscoreDefault.synchronize()
          }
      }
  }
  </code></pre>