ToolTipView.swift

class ToolTipView: UILabel {
    static let shared = ToolTipView()
    enum Anchor {
        case leading
        case trailing
        case center
    }
    
    private var anchor: Anchor = .leading
    
    private var labelTransform: CGAffineTransform!
    
    private init() {
        super.init(frame: .zero)
    }

    private override init(frame: CGRect) {
        super.init(frame: .zero)
        self.numberOfLines = 0
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override var intrinsicContentSize: CGSize {
        let size = super.intrinsicContentSize
        return CGSize(width: size.width + 9 + 8,
                      height: size.height + 8 + 8)
    }
    
    override var bounds: CGRect {
        didSet {
            // ensures this works within stack views if multi-line
            preferredMaxLayoutWidth = bounds.width - (8 + 8)
        }
    }
    
    func display(with anchor: Anchor, in view: UIView, below actionView: UIView) {
        self.anchor = anchor
        switch anchor {
        case .center:
            self.centerXAnchor(equalTo: actionView.centerXAnchor)
        case .leading:
            self.leadingAnchor(equalTo: actionView.leadingAnchor, constant: -16)
            self.trailingAnchor(equalTo: view.trailingAnchor, constant: -16)
        case .trailing:
            self.trailingAnchor(equalTo: actionView.trailingAnchor)
            self.leadingAnchor(equalTo: view.leadingAnchor, constant: 16)
        }
        self.centerYAnchor(equalTo: actionView.centerYAnchor, constant: -48)
        
        let trans1 =  CGAffineTransform(scaleX: 0, y: 0)
        let trans2 =  CGAffineTransform(translationX: 0, y: self.frame.size.height)
        labelTransform = trans1.concatenating(trans2)
        self.transform = labelTransform
        
        UIView.animate(withDuration: 0.75, delay: 0,
                       usingSpringWithDamping: 0.7,
                       initialSpringVelocity: 0.5,
                       options: .curveEaseIn,
                       animations: { () -> Void in
            self.transform = .identity
        })
    }
    override func draw(_ rect: CGRect) {
        let roundRect = CGRect(x: rect.minX, y: rect.minY, width: rect.width, height: rect.height)
        textAlignment = .center
        let trianglePath = UIBezierPath()
        switch anchor {
        case .center:
            trianglePath.move(to: CGPoint(x: roundRect.midX - 12, y: roundRect.maxY))
            trianglePath.addLine(to: CGPoint(x: roundRect.midX + 12, y: roundRect.maxY))
            trianglePath.addLine(to: CGPoint(x: roundRect.midX, y: roundRect.maxY + 12))
        case .leading:
            trianglePath.move(to: CGPoint(x: roundRect.minX + 24, y: roundRect.maxY))
            trianglePath.addLine(to: CGPoint(x: roundRect.minX + 12, y: roundRect.maxY))
            trianglePath.addLine(to: CGPoint(x: roundRect.minX + 24, y: roundRect.maxY + 12))
        case .trailing:
            trianglePath.move(to: CGPoint(x: roundRect.maxX - 24, y: roundRect.maxY))
            trianglePath.addLine(to: CGPoint(x: roundRect.maxX-12, y: roundRect.maxY))
            trianglePath.addLine(to: CGPoint(x: roundRect.maxX-12, y: roundRect.maxY + 12))
        }
        
        trianglePath.close()
        let shapeTriangle = CAShapeLayer()
        shapeTriangle.path = trianglePath.cgPath
        shapeTriangle.fillColor = UIColor.toolTipColor.cgColor
        
        layer.insertSublayer(shapeTriangle, at: 0)
        let insets = UIEdgeInsets(top: 4, left: 8, bottom: 4, right: 8)
        
        let bezierPath = UIBezierPath(roundedRect: self.bounds, cornerRadius: 8)
        UIColor.toolTipColor.setFill()
        bezierPath.fill()
        super.drawText(in: rect.inset(by: insets))
    }
}

extension ToolTipView {
    func create(with text: String, with anchor: Anchor, placeHolderView: UIView, from actionView: UIView)  {
        self.text = text
        self.font = UIFont.preferredCustomFont(forTextStyle: .body)
        self.anchor = anchor
        placeHolderView.addSubview(self)
        self.display(with: self.anchor, in: placeHolderView, below: actionView)
        self.text = text
        self.numberOfLines = 0
        self.textColor = .toolTipTextColor
        self.setNeedsDisplay()
        Queue.main(.seconds(4), .userInitiated) {
            self.removeFromSuperview()
        }
    }
}

extension UIView {
    func showTooltip(with text: String, behind subview: UIView) {
        ToolTipView.shared.create(with: text, with: .center, placeHolderView: self, from: subview)
    }
}

extension UIColor {
    static var toolTipColor: UIColor {
        UIColor(red: 204/255, green: 205/255, blue: 226/255, alpha: 1)
    }
    static var toolTipTextColor: UIColor {
        UIColor(red: 81/255, green: 118/255, blue: 155/255, alpha: 1)
    }
}



final class Queue {
    public static func main(_ after: DispatchTimeInterval = .milliseconds(0),
                              _ service: DispatchQoS = .userInteractive ,
                              _ closure: @escaping () -> Void) {
        DispatchQueue.main.asyncAfter(deadline: .now() + after,
                                      qos: service,
                                      execute: closure)
    }

    public static func onGlobal(_ after: DispatchTimeInterval = .milliseconds(0),
                                _ service: DispatchQoS = .utility ,
                                _ closure: @escaping () -> Void) {
        DispatchQueue.global(qos: .userInitiated)
            .asyncAfter(deadline: .now() + after,
                        qos: service,
                        execute: closure)
    }
}