DropDownTitleView.swift

/**
	Copyright (C) 2015 Quentin Mathe
 
	Date:  June 2015
	License:  MIT
 */

import UIKit

open class DropDownTitleView : UIControl {

	open var iconSize = CGSize(width: 12, height: 12) {
		didSet {
			setNeedsLayout()
		}
	}
	// When compiling as a static library with CocoaPods, image assets end ups in the main bundle 
	// rather than the framework bundle:
	// AppName.app/Resources/DropDownMenuKit/Assets.car
	lazy var imageBundle: Bundle = {
		let bundle = Bundle(for: DropDownTitleView.self)
				
		if let podBundleURL = bundle.url(forResource: "DropDownMenuKitAssets", withExtension: "bundle") {
		   guard let podBundle = Bundle(url: podBundleURL) else {
				fatalError("Missing image assets for DropDownMenUKit")
			}
			return podBundle
		} else {
			return bundle
		}
	}()
	open lazy var menuDownImageView: UIImageView = {
		let menuDownImageView = UIImageView(image: self.imageNamed("Ionicons-chevron-up"))

		menuDownImageView.tintColor = UIColor.black
		menuDownImageView.transform = CGAffineTransform(scaleX: 1, y: -1)

		return menuDownImageView
	}()
	open lazy var menuUpImageView: UIImageView = {
		let menuUpImageView = UIImageView(image: self.imageNamed("Ionicons-chevron-up"))

		menuUpImageView.tintColor = UIColor.black

		return menuUpImageView
	}()
	open lazy var imageView: UIView = {
		// For flip animation, we need a container view
		// See http://stackoverflow.com/questions/11847743/transitionfromview-and-strange-behavior-with-flip
		return UIView(frame: CGRect(origin: CGPoint.zero, size: self.iconSize))
	}()
	open lazy var titleLabel: UILabel = {
		let titleLabel = UILabel()

		titleLabel.font = UIFont.boldSystemFont(ofSize: titleLabel.font.pointSize)
		titleLabel.textColor = UIColor.white

		return titleLabel
	}()
	open var title: String? {
		get {
			return titleLabel.text
		}
		set {
			titleLabel.text = newValue
			titleLabel.sizeToFit()
			titleWidth = titleLabel.frame.width
			layoutSubviews()
		}
	}
    private var titleWidth: CGFloat = 0
	open var isUp: Bool { return menuUpImageView.superview != nil }
	open var toggling = false

	// MARK: - Initialization

	override public init(frame: CGRect) {
		super.init(frame: frame)
		setUp()
	}

	required public init?(coder aDecoder: NSCoder) {
		super.init(coder: aDecoder)
	}
	
	// To support adding outlets/actions later and access them during initialization
	override open func awakeFromNib() {
		setUp()
	}

	func setUp() {
		imageView.addSubview(menuDownImageView)

		addSubview(titleLabel)
		addSubview(imageView)

		if #available(iOS 11, *) {
			translatesAutoresizingMaskIntoConstraints = false
		} else {
			autoresizingMask = [.flexibleWidth, .flexibleHeight]
		}

		let recognizer = UITapGestureRecognizer(target: self, action: #selector(DropDownTitleView.toggleMenu))
	
		isUserInteractionEnabled = true
		addGestureRecognizer(recognizer)
		
		title = "Untitled"
	}

	open func imageNamed(_ name: String) -> UIImage {
		return UIImage(named: name, in: imageBundle, compatibleWith: nil)!
	}

	// MARK: - Layout

	private  let spacing: CGFloat = 4
	// For iOS 11 and above
	override open var intrinsicContentSize: CGSize {
		return UIView.layoutFittingExpandedSize
	}

	// For iOS 10 and below
	open override func willMove(toSuperview newSuperview: UIView?) {
		guard let superview = newSuperview else {
			return
		}
		// Will trigger layoutSubviews() without having resize the title view yet
		// e.g. (origin = (x = 0, y = 0), size = (width = 320, height = 44)
		frame = superview.bounds
	}

	// Centers the title when DropDownMenu.selectMenuCell() isn't called while creating the menu
	open override func didMoveToWindow() {
		// Will trigger layoutSubviews() with the title view resized according to autoresizing
		// e.g. (origin = (x = 58, y = 0), size = (width = 211.5, height = 44))
		layoutSubviews()
	}
	
	open override func layoutSubviews() {
		super.layoutSubviews()

		menuDownImageView.frame.size = iconSize
		menuUpImageView.frame.size = iconSize
		imageView.frame.size = iconSize

		let maxTitleWidth = frame.width - 2 * (spacing + imageView.frame.width)
		
		titleLabel.center = CGPoint(x: frame.width / 2, y: frame.height / 2)
		if titleWidth > maxTitleWidth {
			titleLabel.frame.origin.x = spacing + imageView.frame.width
			titleLabel.frame.size.width = maxTitleWidth
		} else {
			titleLabel.frame.size.width = titleWidth
		}

		imageView.frame.origin.x = titleLabel.frame.maxX + spacing
		imageView.center.y = frame.height / 2
	}

	// MARK: - Actions

	@IBAction open func toggleMenu() {
		if toggling {
			return
		}
		toggling = true
		let viewToReplace = isUp ? menuUpImageView : menuDownImageView
		let replacementView = isUp ? menuDownImageView : menuUpImageView
		let options = isUp ? UIView.AnimationOptions.transitionFlipFromTop : UIView.AnimationOptions.transitionFlipFromBottom

		sendActions(for: .touchUpInside)

		UIView.transition(from: viewToReplace,
		                    to: replacementView,
		              duration: 0.4,
		               options: options,
		            completion: { (Bool) in
			self.sendActions(for: .valueChanged)
			self.toggling = false
		})
	}
}