Question

我通过拉下来刷新表格视图。它刷新存储在解析中的歌曲数组。我在应用程序启动时获得了一个版本的数组，但是当我向数组添加内容然后刷新它时，程序再次添加所有内容以及新内容。所以现在除了新项目之外我还有两次重复。我该如何避免重复？

 override func viewDidLoad() {
    super.viewDidLoad()
 getSongs()

    self.refreshControl = UIRefreshControl()
    self.refreshControl.attributedTitle = NSAttributedString(string: "Pull to refresh")
    self.refreshControl.addTarget(self, action: "refresh:", forControlEvents: UIControlEvents.ValueChanged)
    self.table.addSubview(refreshControl)

           // Do any additional setup after loading the view.

}


 func getSongs(){
    let retrieve = PFQuery(className: "Pointer")
    retrieve.findObjectsInBackgroundWithBlock({
        (objects: [AnyObject]?, error: NSError?) -> Void in
        var object = objects as! [PFObject]
        if(error == nil){
            for i in 0...object.count-1{
                //self.ret.append(object[i].valueForKey("user") as! String)

                if (object[i].valueForKey("user")!.objectId == currentUserID){
                    //print(object[i].valueForKey("title") as! String)
                    self.ret.append(object[i].valueForKey("title") as! String)
                    self.ter.append(object[i].valueForKey("artist") as! String)
                    print(self.ret)
                    print(self.ter)
                }
            }
        }

    })

}

func refresh(sender: AnyObject){
    getSongs()
    table.reloadData()
    self.refreshControl.endRefreshing()
}

Answer 1

@Tim是对的。您必须先刷新数据。

func getSongs(){
    let retrieve = PFQuery(className: "Pointer")
    retrieve.findObjectsInBackgroundWithBlock({
        (objects: [AnyObject]?, error: NSError?) -> Void in
        var object = objects as! [PFObject]
        if(error == nil){

            // refresh data 
            self.ret = []
            self.ter = []

            for i in 0...object.count-1{
                //self.ret.append(object[i].valueForKey("user") as! String)

                if (object[i].valueForKey("user")!.objectId == currentUserID){
                    //print(object[i].valueForKey("title") as! String)
                    self.ret.append(object[i].valueForKey("title") as! String)
                    self.ter.append(object[i].valueForKey("artist") as! String)
                    print(self.ret)
                    print(self.ter)
                }
            }
        }

    })

}

Answer 2

self.ret = []
self.ter = []

在开始附加新数据以清除阵列之前放置这些。

如何防止表格视图产生双打？

2 个答案: