arrays - 加载数组中的数据

Question

当我进入 View Controller 时，我想在数组中加载数据。当我打印数组时，它是空的，但是如果我使用刷新并再次打印数组，他就会被加载。它是代码:

var information = [String]()

override func viewDidLoad() {
    super.viewDidLoad()
    loadinformation()
    print(information)
}

func loadinformation() {
    let ref = Database.database().reference()
    let uid = Auth.auth().currentUser?.uid
    let prof = ref.child("users").child(uid!).child("interess")
    prof.observeSingleEvent(of: .value,with: { (snapshot) in
        if let dict = snapshot.value as? [String: Any] {
            let name = dict["FullName"] as! String
            self.information.append(name)
        }
    })


}

Answer 1

这一行

prof.observeSingleEvent(of: .value,with: { (snapshot) in

是异步的，这意味着它不作为代码的串行流运行，你需要在这里打印它

let name = dict["FullName"] as! String
self.information.append(name)
print(self.information)

//

或者使用补全

func loadinformation(completion:@escaping(_ arr:[String]?) -> Void ) {
    var arr = [String]()
    let ref = Database.database().reference()
    let uid = Auth.auth().currentUser?.uid
    let prof = ref.child("users").child(uid!).child("interess")
    prof.observeSingleEvent(of: .value,with: { (snapshot) in
        if let dict = snapshot.value as? [String: Any] {
            let name = dict["FullName"] as! String
            arr.append(name)
            completion(arr)
        }
        else {
            completion(nil)
        }
    })

}

打电话

loadinformation { (result) in
  print(result)
  if let content = result {
    self.information = content 
    self.collectionView.reloadData()
  }
}