如何清除TableView并重新加载数据？

Question

我有一个这样的功能，当我用按钮重新加载时，这个功能 collectionViewTable 第二次显示相同的数据。我该如何解决？

func getWallpaperFromDB(){
        let databaseRef = Database.database().reference()
        databaseRef.child("wallpapers").observe(DataEventType.childAdded) { (snapshot) in
            if let value = snapshot.value! as? [String: Any] {
                let categoryID = value["categoryID"] as! String
                let categoryName = value["categoryName"] as! String
                let wallpaperName = value["wallpaperName"] as! String
                let wallpaperId = snapshot.key
                let DBWallpaper = Wallpaper(categoryID: categoryID, categoryName: categoryName, wallpaperId: wallpaperId, wallpaperName: wallpaperName)
                self.wallpapers.append(DBWallpaper)
                self.collectionViewTable.reloadData()
            }

        }
    }

@IBAction func slideMenuButton(_ sender: Any) {
        getWallpaperFromDB()
    }

Answer 1

你需要清除每一个电话

@IBAction func slideMenuButton(_ sender: Any) {
    wallpapers.removeAll()
    getWallpaperFromDB()
}

Answer 2

你可以在闭包函数中清空你的壁纸数组。 这样每次调用该函数时，壁纸数组都会在再次获取数据之前为空。 这样你就不会有重复的数据。

func getWallpaperFromDB(){

        let databaseRef = Database.database().reference()
        databaseRef.child("wallpapers").observe(DataEventType.childAdded) { (snapshot) in
            
            self.wallpapers = [] 
            
            if let value = snapshot.value! as? [String: Any] {
                let categoryID = value["categoryID"] as! String
                let categoryName = value["categoryName"] as! String
                let wallpaperName = value["wallpaperName"] as! String
                let wallpaperId = snapshot.key
                let DBWallpaper = Wallpaper(categoryID: categoryID, categoryName: categoryName, wallpaperId: wallpaperId, wallpaperName: wallpaperName)
                self.wallpapers.append(DBWallpaper)
                self.collectionViewTable.reloadData()
            }

        }
    }

@IBAction func slideMenuButton(_ sender: Any) {
        getWallpaperFromDB()
    }