ios - 如何在 UITextView、Swift3 和 Parse 服务器上显示数组元素 (bitnami)

Question

我是 swift/Parse 服务器的新手，正在努力显示存储在 Parse 服务器中的数组元素 (bitnami)。

它终于按照我想要的方式工作了，但是看起来非常奇怪，我不明白为什么它工作得很好。

有谁能理解它为什么起作用吗？

1. ViewController.swift

   query?.limit = 1
   
   query?.findObjectsInBackground(block: {(objects,error) in
       if let users = objects {
   
           for object in users {
   
               if let user = object as? PFUser {
   
                   self.userName.text = user.username!
   
   
                   if let userCarType = user["carType"] as? Array<Any>{
   
   
                       self.carTypeText.text = userCarType[0] as! String
   
   
                   }
   

2. 解析服务器

列:carType(数组)

值:“丰田、福特”

它如何在 UITextField 上显示:

丰田、福特

Answer 1

下面是代码的一些解释，如果您需要更多解释，请告诉我。

    let query = PFQuery(className:"UserCarTypes") /// name of your table
    query.includeKey("UserPointer") // if you have pointers like user (and you want to load this data also)
    query.whereKey("x", equalTo: false) // set some conditions in query if needed
    query.findObjectsInBackground { (objects: [PFObject]?, error: Error?) in

        // query always returns the objects (rows) in a [PFObject] array

        // first check for error or nil
        if error != nil {
            print(error!)
            return
        }

        if objects?.count == 0 || objects == nil {
            print("no data retrieved")
            return
        }

        //loop throught objects
        if let users = objects {
            for object in users {

                //set user label
                if let user = object as? PFUser {
                    self.userName.text = user.username! // set username on text label (this assumes there is always a username, otherwise your app will crash)

                }

                //set carType label
                if let userCarType = user["carType"] as? NSArray { // downcast the row data from the PFObject to an Array
                    if let first_car = userCarType[0] as? String { // set the first value of your array of userCarType: Toyota
                        if let second_car = userCarType[1] as? String { // set the second value of your array: Ford
                            self.carTypeText.text = "\(first_car),\(second_car)" // set both car types on the TextLabel
                        } else {
                            self.carTypeText.text = "\(first_car)" // set only the first car type on the TextLabel
                        }
                    }
                }
            }
        }
    }