PlaceholderTextView.swift

PlaceholderTextView.swift

import UIKit

@IBDesignable
final class PlaceholderTextView: UITextView, UITextViewDelegate {

    private let _TAG = 100

    override open var bounds: CGRect {
        didSet {
            self.resizePlaceholder()
        }
    }

    override var font: UIFont? {
        didSet {
            self.resizePlaceholder()
        }
    }

    @IBInspectable var placeholder: String? {
        get {
            if let label = self.viewWithTag(_TAG) as? UILabel {
                return label.text
            } else {
                return nil
            }
        }
        set {
            if let label = self.viewWithTag(_TAG) as? UILabel {
                label.font = self.font
                label.text = newValue
                label.sizeToFit()
            } else {
                self.addPlaceholder(with: newValue)
            }
        }
    }

    public func textViewDidChange(_ textView: UITextView) {
        if let label = self.viewWithTag(_TAG) as? UILabel {
            label.isHidden = !self.text.isEmpty
        }
    }

    private func resizePlaceholder() {
        if let label = self.viewWithTag(_TAG) as? UILabel {
            label.font = self.font
            label.sizeToFit()
            let x = self.textContainer.lineFragmentPadding
            let y = self.textContainerInset.top - 2
            let width = self.frame.width - (x * 2)
            let height = label.frame.height

            label.frame = CGRect(x: x, y: y, width: width, height: height)
        }
    }

    private func addPlaceholder(with text: String?) {
        guard let text = text else { return }

        let label = UILabel()
        label.text = text
        label.textColor = UIColor(hex: "#C7C7CD")
        label.tag = _TAG
        label.isHidden = !self.text.isEmpty

        self.addSubview(label)
        self.resizePlaceholder()
        self.delegate = self
    }
}