Swift: Move UILabel up when keyboard appears

Question

I'm having trouble finding out how to move a UILabel up when the keyboard appears.

Currently, the label sits about 140 pixels from the top and sits perfectly centre when the keyboard appears when I simulating using iPhone 7.

However, when using the smaller iPhone 5, I have this issue.

where the keyboard overlaps the UILabel.

What I'm trying to do is to centre the UILabel as the keyboard appears.

Most tutorials are showing how to move a UITextField up but I tried to apply the same aspect for the UILabel but failed.

Answer 1

One possible solution to move controls up when the keyboard appears is to add bottom constraints to the controls and define outlets to those constraints.

 @IBOutlet weak var controlBottomConstraint: NSLayoutConstraint!

In viewDidLoad register a keyboardWillShow method to receive the notification when the keyboard appears like:

NotificationCenter.default.addObserver(self, selector: #selector(MyViewController.keyboardWillShow(_:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

Then in the keyboardWillShow method update the constraint (controlBottomConstraint) like this:

func keyboardWillShow(_ notification:Notification) {
  ...
    let userInfo:NSDictionary = (notification as NSNotification).userInfo! as NSDictionary
    let keyboardFrame:NSValue = userInfo.value(forKey: UIKeyboardFrameEndUserInfoKey) as! NSValue
    let keyboardRectangle = keyboardFrame.cgRectValue
    let keyboardHeight = keyboardRectangle.height
  // controlBottomConstraint outlet to the control you want to move up
  controlBottomConstraint.constant = keyboardHeight + 8
}

It also works when rotating the device.

Answer 2

First ViewController

  import UIKit

    class ViewController: UIViewController , UITableViewDelegate ,UITableViewDataSource, UITextViewDelegate {

        @IBOutlet weak var ViewSend: UIView!
        @IBOutlet weak var txtMessage: UITextView!
        @IBOutlet weak var ChatTable: UITableView!
        var chatArray:[String] = []
          var collect:String!
        override func viewDidLoad()
        {
            super.viewDidLoad()
            txtMessage.delegate = self
           NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
           NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
           print(self.ViewSend.frame.origin.y)

        }
        override func didReceiveMemoryWarning()
        {
            super.didReceiveMemoryWarning()
        }
        func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
        {
            return chatArray.count
        }
        func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
            let cell = tableView.dequeueReusableCell(withIdentifier: "CellDemo") as! chatlableTableViewCell
            let obj = chatArray[indexPath.row]
            cell.lblchat.text = obj
            cell.lblchat.sizeToFit()
            cell.lblchat.layer.cornerRadius = 2
            cell.lblchat.clipsToBounds = true
            return cell
        }


        @IBAction func btnSendPresssed(_ sender: UIButton)
        {
                if txtMessage.text == ""
                {

                }
                else
                {

                    collect =  txtMessage.text
                    chatArray.append(collect)
                }
            ChatTable.reloadData()
            txtMessage.text = ""
        }
        func calcheight(strin:String) -> CGFloat
        {
            let label =  UILabel(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: CGFloat.greatestFiniteMagnitude))
            label.numberOfLines = 0
            label.text = strin
            label.sizeToFit()
            return label.frame.height + 2

        }
        func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat
        {
            let height = self.calcheight(strin: String(describing: chatArray[indexPath.row]))
            return height

        }
        func keyboardWillShow(notification: NSNotification) {

            if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue
            {
                if self.ViewSend.frame.origin.y != keyboardSize.height
                {
                    self.ViewSend.frame.origin.y -= keyboardSize.height
                    self.ChatTable.frame.size.height -= keyboardSize.height
                }
           }
        }
        func keyboardWillHide(notification: NSNotification)
        {

           if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue
           {
                self.ViewSend.frame.origin.y += keyboardSize.height
            self.ChatTable.frame.size.height += (keyboardSize.height + ViewSend.frame.size.height)

           }   

        }

    }

TableView Cell

import UIKit

class chatlableTableViewCell: UITableViewCell {

    @IBOutlet weak var lblchat: UILabel!
    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        // Configure the view for the selected state
    }

}

Answer 3

Try this: make an extension and add notification observers

class ViewController: UIViewController {
   var keyboardOnScreen = false

    @IBOutlet weak var searchBar: UISearchBar!
    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name:.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: .UIKeyboardWillHide, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidShow), name: .UIKeyboardDidShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidHide), name: .UIKeyboardDidHide, object: nil)

        searchBar.delegate = self
    }

}
extension ViewController: UISearchBarDelegate {

    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }


    func keyboardWillShow(_ notification: Notification) {
        if !keyboardOnScreen {
            view.frame.origin.y -= keyboardHeight(notification)        }
    }

    func keyboardWillHide(_ notification: Notification) {
        if keyboardOnScreen {
            view.frame.origin.y += keyboardHeight(notification)
        }
    }

    func keyboardDidShow(_ notification: Notification) {
        keyboardOnScreen = true
    }

    func keyboardDidHide(_ notification: Notification) {
        keyboardOnScreen = false
    }

    private func keyboardHeight(_ notification: Notification) -> CGFloat {
        let userInfo = (notification as NSNotification).userInfo
        let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
        return keyboardSize.cgRectValue.height
    }

    private func resignIfFirstResponder(_ textField: UITextField) {
        if textField.isFirstResponder {
            textField.resignFirstResponder()
        }
    }

    @IBAction func userDidTapView(_ sender: AnyObject) {
        resignIfFirstResponder(textField)
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.view.endEditing(true)
    }

}

Answer 4

If you are doing constraints just change the multiplier to 0.5. If you are doing frame, set the frame's y position (yourLabel.frame.origin.y) to self.view.frame.height / 2.