Firebase：iOS：Firebase读取后数组为空

Question

我正在使用存储在结构中的数组来存储来自 firebase 数据库的条目。我可以成功地加载数据，因为我可以打印出数据库的每个项目。然而，一个名为 allMovies 的数组在某种程度上是空的，即使我只是用来自 firebase 的数据填充它。

为什么会这样？

这是我的代码：

保存我的数组的全局结构及其更改在整个程序中都是可见的。

struct GlobalMovies {
    static var allMovies:[Movies] = []
    static var hotMovies:[Movies] = []
    static var upcomingMovies:[Movies] = []
}

从我的 firebase 读取数据的功能。如前所述，我能够成功读取数据。

var ref:DatabaseReference?
var databaseHandle:DatabaseHandle?

databaseHandle = ref?.child("Movies").observe(.childAdded, with: { (snapshot) in
if let userDict = snapshot.value as? [String:Any] {

                GlobalMovies.allMovies.append(Movies(name: userDict["name"]! as! String ,
                                                     rating: userDict["rating"]! as! String,
                                                     length: userDict["length"]! as! String,
                                                     genre: userDict["genre"]! as! String ,
                                                     cast : userDict["cast"] as! [String],
                                                     cinemas : userDict["cinemas"] as! [String],
                                                     releaseDate: userDict["releaseDate"]! as! String,
                                                     director: userDict["director"]! as! String,
                                                     description: userDict["description"]! as! String ,
                                                     image: userDict["image"]! as! String,
                                                     isHot: userDict["isHot"]! as! Bool,
                                                     isUpcoming: userDict["isUpcoming"]! as! Bool))
                self.table.reloadData()


            }
        })
        print(GlobalMovies.allMovies.count)   //prints out 0 when it shouldn't

我的json文件：

{
    "Movies": {
        "Movie1" : {
            "name": "The Incredible Hulk",
            "rating": "4/5",
            "length": "120 minutes",
            "genre": "Fantasy",
            "cast" : ["Lisa Simpson", "Peter Griffin"],
            "cinemas": ["A", "B"],
            "releaseDate": "12/05/2018",
            "director": "Mike Lancaster", 
            "description" : "Lorem Ipsum",
            "image": "default",
            "isHot": true,
            "isUpcoming": false
        },
        "Movie2" : {
            "name": "Star Wars",
            "rating": "5/5",
            "length": "120 minutes",
            "genre": "SciFi",
            "cast" : ["Lisa Simpson", "Peter Griffin"],
            "cinemas": ["A", "B"],
            "releaseDate": "12/05/2018",
            "director": "Mike Lancaster", 
            "description" : "Lorem Ipsum",
            "image": "default",
            "isHot": true,
            "isUpcoming": false
        }


    }
}

Answer 1

原因是因为 firebase 异步获取数据，所以当您进行打印时，它还没有获取数据，但过了一段时间它会获取它们。您要做的是在获取完成后打印数据