为什么我的关注按钮会被调用两次？

Question

所以我有一个跟随按钮，第一次点击它时效果很好。以下计数加1，按钮标题更改为＆＃34;取消关注＆＃34;。当我点击按钮时，标题成功更改回＆＃34;关注＆＃34;但是下面的计数减少了2而不是1.这是我的问题。所以这个方法被调用了两次。我一直试图弄清楚如何解决这个问题，但我似乎无法弄明白。非常感谢帮助。提前谢谢！

  class guestProfileViewController: UIViewController, UINavigationControllerDelegate, UICollectionViewDelegateFlowLayout {

    @IBOutlet weak var followButton: CustomizableButton!

    var ref: DatabaseReference?

    var otherUser: userAccount!
    let loggedInUser = Auth.auth().currentUser
    var loggedInUserData: userAccount!

    override func viewDidLoad() {
        super.viewDidLoad()

        loadButtonView()
    }

 func loadButtonView(){
  Database.database().reference().child("following").child(self.loggedInUser!.uid).child(self.otherUser.uid!).observe(.value, with: 
    { (snapshot) in

    if(snapshot.exists())
    {
    self.followButton.setTitle("Unfollow", for: .normal)
    self.followButton.backgroundColor = .white
    self.followButton.setTitleColor(UIColor.rgb(red: 17, green: 154, blue: 237)
    , for: .normal)

    print("You are following the user") 
    }else{
    self.followButton.setTitle("Follow", for: .normal)
    self.followButton.setTitle("Follow", for: .normal)
    self.followButton.backgroundColor = UIColor.rgb(red: 17, green: 154, blue: 237)
    self.followButton.setTitleColor(.white, for: .normal)
    self.followButton.layer.borderColor = UIColor(white: 0, alpha: 0.2).cgColor

    print("you are not following user")
    }
    })

   { (error) in     
  print(error.localizedDescription)
    }

    }

    @IBAction func followButton(_ sender: CustomizableButton) {


        let ref = Database.database().reference().child("user").child(loggedInUser!.uid)
        ref.observeSingleEvent(of: .value, with: { (snapshot) in
            let dictionary = snapshot.value as? NSDictionary

         let loggedInFollowingCount = dictionary?["followingCount"] as! Int

        let followersRef = "followers/\(self.otherUser.uid! as String)/\(self.loggedInUser!.uid)"
        let followingRef = "following/" + (self.loggedInUser!.uid) + "/" + (self.otherUser.uid! as String)


        if(self.followButton.titleLabel?.text == "Follow")
        {

            let ref = Database.database().reference().child("user").child(self.loggedInUser!.uid)
            ref.observeSingleEvent(of: .value, with: { (snapshot) in
                let dictionary = snapshot.value as? [String: Any]

                let followersData = ["fullName": dictionary?["fullName"] as? String, "profilePic": dictionary?["profilePic"]as? String,"followersCount": dictionary?["followersCount"] as? String,"countryFlagImage": dictionary?["countryFlagImage"] as? String, "userID": dictionary?["uid"] as? String]

                let followingData = ["fullName":self.otherUser.fullName! as String, "profilePic": self.otherUser.profilePic! as String, "followersCount": self.otherUser.followersCount as Int, "countryFlagImage": self.otherUser.countryFlagImage!, "userID": self.otherUser.uid!] as [String : Any]


                let childUpdates = [followersRef:followersData,
                                    followingRef:followingData]

                Database.database().reference().updateChildValues(childUpdates)

                print("data updated")
            })

        Database.database().reference().child("user").child(self.loggedInUser!.uid).child("followingCount").setValue(loggedInFollowingCount + 1)

           Database.database().reference().child("user").child((self.otherUser?.uid)!).child("followersCount").setValue((self.otherUser!.followersCount) as Int + 1)

            }

        else
        {

            Database.database().reference().child("user").child(self.loggedInUser!.uid).child("followingCount").setValue(loggedInFollowingCount - 1)

            Database.database().reference().child("user").child((self.otherUser?.uid)!).child("followersCount").setValue((self.otherUser!.followersCount) as Int - 1)

            let followersRef = "followers/\(self.otherUser.uid! as String)/\(self.loggedInUser!.uid)"
            let followingRef = "following/" + (self.loggedInUser?.uid)! + "/" + (self.otherUser?.uid)!


            let childUpdates = [followingRef:NSNull(),followersRef:NSNull()]
            Database.database().reference().updateChildValues(childUpdates)

            }

        })
    }