无法返回字符串数组中的项目

Question

我是 Parse 和 Swift 的新手，我正在处理这个项目，我正在尝试创建一个搜索栏，显示我的 Parse 数据库中关键“名称”中的所有项目。

我创建了这个函数，它应该获取所有名称并将它们返回到一个字符串数组中。但相反，数组永远不会被填充，我得到的只是 []。

class Offices {
    var name: String
    var phone: String
    var location: String
    
    init(name: String = "def_name", phone: String = "def_phone", location: String = "def_location") {
        self.name = name
        self.phone = phone
        self.location = location
    }
    func retrieveName() -> [String] {
        var models = [String]()
        let queries = PFQuery(className: "Directory")
        queries.findObjectsInBackground { (object, error) in
            if let error = error {
                // The query failed
                print(error.localizedDescription)
            } else if let object = object {
                // The query succeeded with a matching result
                for i in object{
                    models.append(i["name"] as? String ?? self.name)
                }
                
            } else {
                // The query succeeded but no matching result was found
            }
            
        }
        return models
    }

Answer 1

findObjectsInBackground 方法是异步的。所以你应该改变retrieveName函数如下：

class Offices {
    var name: String
    var phone: String
    var location: String
    
    init(name: String = "def_name", phone: String = "def_phone", location: String = "def_location") {
        self.name = name
        self.phone = phone
        self.location = location
        
        // I call retrieveName here for example. You can call it where you want.
        retrieveName() { (success, models) in
            if success {
                print(models)
            } else {
                print("unsuceess")
            }
        }
    }

    func retrieveName(completion: @escaping (_ success: Bool, _ models: [String]) -> Void) {
        var models = [String]()
        let queries = PFQuery(className: "Directory")
        queries.findObjectsInBackground { (object, error) in
            if let error = error {
                // The query failed
                print(error.localizedDescription)
                completion(false, [])
            } else if let object = object {
                // The query succeeded with a matching result
                for i in object{
                    models.append(i["name"] as? String ?? self.name)
                }
                completion(true, models)
            } else {
                completion(true, [])
                // The query succeeded but no matching result was found
            }
        }
    }
}