Add Placeholder to UITextView

UITextViewWithPlaceholder.swift

class UITextViewWithPlaceholder: UITextView, UITextViewDelegate {
    private var placeholderLabel: UILabel?;
    
    required init?(coder: NSCoder){
        super.init(coder: coder)
        self.delegate = self;
    }
    
    func setPlaceholder(text: String, color: UIColor = Constants.View.whiteColor.withAlphaComponent(0.5)) {
        if (self.placeholderLabel == nil) {
            let placeholderLabel = UILabel();
            placeholderLabel.text = text;
            placeholderLabel.font = self.font;
            placeholderLabel.textColor = color;
            placeholderLabel.sizeToFit()
            placeholderLabel.frame.origin = CGPoint(x: 5, y: (placeholderLabel.font?.pointSize)! / 2)
            placeholderLabel.isHidden = self.text == nil || !self.text!.isEmpty
            
            self.placeholderLabel = placeholderLabel;
            self.addSubview(self.placeholderLabel!)
        }
    }
    
    func textViewDidChange(_ textView: UITextView) {
        let view = textView as! UITextViewWithPlaceholder;
        if (view.placeholderLabel != nil) {
            view.placeholderLabel!.isHidden = view.text == nil || !view.text!.isEmpty
        }
    }
}

// Usage
class ViewController: UIViewController {
    @IBOutlet weak var textView: UITextViewWithPlaceholder!
    
    override func viewDidLoad() {
        super.viewDidLoad();
        
        self.textView.setPlaceholder(text: "Placeholder...");
    }
}