PlaceholderTextView

gistfile1.swift

final class PlaceholderTextView: UITextView {
    private lazy var placeholderLabel: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.backgroundColor = .clear
        label.isUserInteractionEnabled = false
        label.textColor = .neutralDark600
        label.numberOfLines = 0
        label.font = .systemFont(ofSize: 14, weight: .medium)
        return label
    }()

    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        setupView()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupView()
    }
    
    override var text: String! {
        didSet {
            placeholderLabel.isHidden = text.isNotEmpty
        }
    }
    
    override var textContainerInset: UIEdgeInsets {
        didSet {
            NSLayoutConstraint.activate([
                placeholderLabel.leadingAnchor.constraint(equalTo: self.safeAreaLayoutGuide.leadingAnchor, constant: textContainerInset.left),
                placeholderLabel.trailingAnchor.constraint(equalTo: self.safeAreaLayoutGuide.trailingAnchor, constant: -textContainerInset.right),
                placeholderLabel.topAnchor.constraint(equalTo: topAnchor, constant: textContainerInset.top)
            ])
        }
    }
    
    // MARK: - Public

    var placeholder: String? {
        get {
            return placeholderLabel.text
        }
        set {
            placeholderLabel.text = newValue
        }
    }
    
    var placeholderColor: UIColor? {
        set {
            placeholderLabel.textColor = newValue ?? .neutralDark600
        }
        get {
            return placeholderLabel.textColor
        }
    }
    
    override func becomeFirstResponder() -> Bool {
        placeholderLabel.isHidden = true
        return super.becomeFirstResponder()
    }
    
    override func resignFirstResponder() -> Bool {
        placeholderLabel.isHidden = text.isNotEmpty
        return super.resignFirstResponder()
    }

    // MARK: - Private

    private func setupView() {
        placeholderLabel.font = font
        addSubview(placeholderLabel)
    }
}