我有一個 UILabel 僅當我的 UITableView 為空時才可見。 如何在 Swift 中將該標簽的文本居中？

Question

我的應用程序中有一個UITableView ，我想在沒有內容時顯示一個UILabel 。 到目前為止，我正在做：

@IBOutlet var tview: UITableView!

var emptyLabel = UILabel(frame: CGRectMake(0, 10, 100, 100))

override func viewDidLoad(){

    let refreshControl = UIRefreshControl()

    refreshControl.addTarget(self, action: "refresh:", forControlEvents: .ValueChanged)
    refreshControl.attributedTitle = NSAttributedString(string: "last updated on \(NSDate())")

    tview.separatorStyle = UITableViewCellSeparatorStyle.None
    tview.addSubview(refreshControl)


    emptyLabel.numberOfLines = 0
    emptyLabel.text = "There is no content in this table for now. Please pull down the list to refresh and something should appear"
    emptyLabel.font = emptyLabel.font.fontWithSize(10)
    tview.backgroundView = emptyLabel
}

但是當我這樣做時，我有以下結果：

而不是向左對齊，我想將文本居中，使其看起來像：

       There is no content in this table for now. Please pull down the
                list to refresh and something should appear

另外，目前它是垂直居中的 - 有沒有辦法把這條消息放在屏幕頂部的 1/3 處？

====== 編輯

@Md.Muzahidul Islam 這就是我在表格為空時顯示標簽的方式：

override func tableView(tview: UITableView, numberOfRowsInSection section: Int) -> Int {

    if self.items.count == 0{
        self.emptyLabel.hidden = false
        return 0
    } else {
        self.emptyLabel.hidden = true
    return self.items.count;
    }
}

Answer 1

您可以通過以下方式實現：

override func viewDidLoad()
{
   // Other codes
   emptyLabel               = UILabel(frame: CGRectMake(0, 0, tview.bounds.size.width, view.bounds.size.height))
   emptyLabel.textAlignment = NSTextAlignment.Center
   emptyLabel.numberOfLines = 0
   emptyLabel.text          = "There is no content in this table for now. Please pull down the list to refresh and something should appear"
   emptyLabel.font          = emptyLabel.font.fontWithSize(10)
   tview.backgroundView     = emptyLabel
}

你可以在這里閱讀更多關於它的信息

Answer 2

斯威夫特3.0

我希望它服務於你的目的......在你的 UITableViewController 中。

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    if searchController.isActive && searchController.searchBar.text != "" {
        if filteredContacts.count > 0 {
            self.tableView.backgroundView = .none;
            return filteredContacts.count
        } else {
            Helper.EmptyMessage(message: ConstantMap.NO_CONTACT_FOUND, viewController: self)
            return 0
        }
    } else {
        if contacts.count > 0 {
            self.tableView.backgroundView = .none;
            return contacts.count
        } else {
            Helper.EmptyMessage(message: ConstantMap.NO_CONTACT_FOUND, viewController: self)
            return 0
        }
    }
}

具有功能的助手類：

 /* Description: This function generate alert dialog for empty message by passing message and
           associated viewcontroller for that function
           - Parameters:
            - message: message that require for  empty alert message
            - viewController: selected viewcontroller at that time
         */
        static func EmptyMessage(message:String, viewController:UITableViewController) {
            let messageLabel = UILabel(frame: CGRect(x: 0, y: 0, width: viewController.view.bounds.size.width, height: viewController.view.bounds.size.height))
            messageLabel.text = message
            let bubbleColor = UIColor(red: CGFloat(57)/255, green: CGFloat(81)/255, blue: CGFloat(104)/255, alpha :1)

            messageLabel.textColor = bubbleColor
            messageLabel.numberOfLines = 0;
            messageLabel.textAlignment = .center;
            messageLabel.font = UIFont(name: "TrebuchetMS", size: 18)
            messageLabel.sizeToFit()

            viewController.tableView.backgroundView = messageLabel;
            viewController.tableView.separatorStyle = .none;
        }