Beginnings of a floating label text view

FloatingTextView.swift

//
//  FloatingTextView.swift
//  DocumentsUI
//
//  Created by Spencer Whyte on 2018-10-03.
//  Copyright © 2018 Probuild Software Inc. All rights reserved.
//

import UIKit

class FloatingTextView: UITextView {

    var label: String? {
        didSet {
            floatingLabel.text = label
            hintLabel.text = label
        }
    }

    var floatingLabelColor: UIColor = UIColor.lightGray

    private let floatingLabelPadding: CGFloat = 20

    private let floatingLabel: UILabel
    private let hintLabel: UILabel
    private var lastHideFloatingLabel: Bool? = nil

    init() {
        floatingLabel = UILabel()
        hintLabel = UILabel()
        let startDate = Date()
        super.init(frame: CGRect.zero, textContainer: nil)
        print(Date().timeIntervalSince(startDate))
        textContainerInset = UIEdgeInsets(top: 17, left: textContainerInset.left, bottom: textContainerInset.bottom, right: textContainerInset.right)
        setup()
        setupConstraints()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override var text: String! {
        didSet {
            updateLabelVisibility(shouldAnimate: false)
        }
    }

    @objc func textDidChange() {
        updateLabelVisibility(shouldAnimate: true)
    }

    @objc func didBeginEditing() {
        self.floatingLabel.textColor = floatingLabelColor
    }

    @objc func didEndEditing() {
        self.floatingLabel.textColor = UIColor.lightGray
    }

    private func updateLabelVisibility(shouldAnimate: Bool) {
        let hideFloatingLabel = self.text.count == 0
        if shouldAnimate {
            if hideFloatingLabel != lastHideFloatingLabel {
                lastHideFloatingLabel = hideFloatingLabel
                UIView.animate(withDuration: 0.5, delay: 0, options: [UIView.AnimationOptions.curveEaseOut, UIView.AnimationOptions.beginFromCurrentState], animations: {
                    self.updateOpacity(hideFloatingLabel: hideFloatingLabel)
                }, completion: nil)
            }
        } else {
            updateOpacity(hideFloatingLabel: hideFloatingLabel)
        }
    }

    private func updateOpacity(hideFloatingLabel: Bool) {
        let floatingLabelOpacity: CGFloat = hideFloatingLabel ? 0 : 1
        let hintLabelOpacity: CGFloat = hideFloatingLabel ? 1 : 0
        self.floatingLabel.alpha = floatingLabelOpacity
        self.hintLabel.alpha = hintLabelOpacity
    }

    private func setup() {
        isScrollEnabled = false
        NotificationCenter.default.addObserver(self, selector: #selector(textDidChange), name:UITextView.textDidChangeNotification, object: self)
        NotificationCenter.default.addObserver(self, selector: #selector(didBeginEditing), name:UITextView.textDidBeginEditingNotification, object: self)
        NotificationCenter.default.addObserver(self, selector: #selector(didEndEditing), name:UITextView.textDidEndEditingNotification, object: self)

        setupFloatingLabel()
        setupHintLabel()

        updateLabelVisibility(shouldAnimate: false)
    }

    private func setupFloatingLabel() {
        floatingLabel.translatesAutoresizingMaskIntoConstraints = false
        floatingLabel.font = UIFont.systemFont(ofSize: 8)
        floatingLabel.textColor = floatingLabelColor
        addSubview(floatingLabel)
    }

    private func setupHintLabel() {
        hintLabel.translatesAutoresizingMaskIntoConstraints = false
        hintLabel.textColor = UIColor.lightGray
        hintLabel.font = UIFont.systemFont(ofSize: 11)
        addSubview(hintLabel)
    }

    private func setupConstraints() {
        NSLayoutConstraint.activate([
            floatingLabel.topAnchor.constraint(equalTo: topAnchor, constant: 5),
            floatingLabel.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 5),
            hintLabel.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 5),
            hintLabel.topAnchor.constraint(equalTo: floatingLabel.bottomAnchor, constant: 3),
            bottomAnchor.constraint(greaterThanOrEqualTo: hintLabel.bottomAnchor),
            heightAnchor.constraint(greaterThanOrEqualToConstant: 50)
            ])
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

}