There are instances where we need to use UITextView as a multi-line text field in our app. The UITextView does not provide a placeholder property like the UITextField. So, in order to achieve this we need to implement the following methods in our UIViewController:

class DemoVC: UIViewController, UITextViewDelegate {

//hook this to the storyboard UITextView
@IBOutlet weak var descriptionTxtView: UITextView!

func textViewDidBeginEditing(_ textView: UITextView) {
        if descriptionTxtView.text == "Add description..." {
            descriptionTxtView.text = ""
            descriptionTxtView.textColor = UIColor.black
        }
    }
    
    func textViewDidEndEditing(_ textView: UITextView) {
        if descriptionTxtView.text == "" {
            descriptionTxtView.text = "Add description..."
            descriptionTxtView.textColor = #colorLiteral(red: 0.4922404289, green: 0.7722371817, blue: 0.4631441236, alpha: 1)
        }
    }

}

Please note in the above code that the View Controller class also conforms to the UITextViewDelegate. All of the methods in the protocol are optional, however use them to adjust the text as needed.

The above code is implemented using Swift 4.