swift - 如何设置值为 firebase 的条形按钮？

Question

我想检查用户是否是管理员。如果用户是管理员，我想显示一个栏按钮。如果不是，则应隐藏栏按钮。

我在 viewDidLoad 中调用以下代码:

@IBOutlet weak var beitraegeMelden: UIBarButtonItem!
var admin = false

func setupBarButton() {
    observeAdmin()
    if admin == true {
        self.beitraegeMelden.isEnabled = true
        self.navigationItem.rightBarButtonItem = self.beitraegeMelden
    } else {
        self.beitraegeMelden.isEnabled = false
        self.navigationItem.rightBarButtonItem = nil
    }
}

func observeAdmin() {
    guard let currentUserUid = UserApi.shared.CURRENT_USER_ID else { return }
    let REF_ADMIN = Database.database().reference().child("users").child(currentUserUid).child("admin")
    REF_ADMIN.observeSingleEvent(of: .value) { (admin) in
        let adminRecht = admin.value as? Bool
        if adminRecht == true {
            self.admin = true
        } else {
            self.admin = false
        }
    }
}

这里是我实际登录用户的数据库结构:

users
    currentUid
        admin: true 

admin 值永远不会变为真。预先感谢您的帮助!

Answer 1

您需要完成，因为对 firebase 的调用是异步的

func observeAdmin(completion:@escaping((Bool) -> () )) {
    guard let currentUserUid = UserApi.shared.CURRENT_USER_ID else { return }
    let REF_ADMIN = Database.database().reference().child("users").child(currentUserUid).child("admin")
    REF_ADMIN.observeSingleEvent(of: .value) { (admin) in
       completion( (admin.value as? Bool) ?? false )
    }
}

---

打电话

observeAdmin { (res) in 
   self.beitraegeMelden.isEnabled = res    
   self.navigationItem.rightBarButtonItem = res ? self.beitraegeMelden : nil
}