ios - swift 数组在循环时不追加

Question

我正在尝试从 Parse 检索数据以附加到我的组数组:

var displayedGroups = [Groups]()

组是一个结构:

struct Groups{
    let name: String?
    let date: Date
    let number: Int
    let id: String

    init(id: String, name: String, date: Date, number: Int) {
        self.id = id
        self.name = name
        self.date = date
        self.number = number
    }
}

这是我尝试检索数据的函数:

func getDisplayedGroups() {
        let query = PFQuery(className: "MeetUps")
        print(PFUser.current()?.username)
        query.whereKey("peeps", contains: PFUser.current()?.username)
        query.findObjectsInBackground { (objects, error) in
            if error != nil {
                print(error)
            } else if let objects = objects {
                for meetUps in objects {
                    let peeps = (meetUps["peeps"] as! [String])
                    let id = meetUps.objectId!
                    //let name = meetUps["meetUpName"] as? String
                    let date = meetUps["when"] as! Date
                    let group = Groups(id: id, name: " ", date: date, number: peeps.count)
                    print(group)
                    self.displayedGroups.append(group)
                }
            }
        }
        for i in displayedGroups {
            print(i)
        }
        tableView.reloadData()
    }

我注释掉了 let name = meetUps["meetUpName"]... 因为在我的解析仪表板的“meetUpName”键列中没有值。

print(group) 有效，它为每个循环打印不同的组。

但是，这个 block :

for i in displayedGroups {
                print(i)
            }

根本不打印 :/因此我的表没有从 displayedGroups 加载数据。它与异步有关吗？应该不对吧？因为他们在同一个街区。我不知道，请指教。谢谢!

Answer 1

findObjectsInBackground 异步工作，将循环和重新加载 TableView 的行放在 完成 block 中。

您可能需要在主线程上重新加载 TableView 。

...
    for meetUps in objects {
      let peeps = (meetUps["peeps"] as! [String])
      let id = meetUps.objectId!
      //let name = meetUps["meetUpName"] as? String
      let date = meetUps["when"] as! Date
      let group = Groups(id: id, name: " ", date: date, number: peeps.count)
      // print(group)
      self.displayedGroups.append(group)
    }
    for i in displayedGroups {
      print(i)
    }
    dispatch_async(dispatch_get_main_queue) {
       self.tableView.reloadData()
    }
...