UICValueLabeledSlider.swift

//
//  UICAwesomeSlider.swift
//
//  Created by Coder ACJHP on 15.04.2019.
//  Copyright © 2019 FitBest Bilgi Teknolojileri. All rights reserved.
//

import UIKit

class UICValueLabeledSlider: UISlider {

    let currentValueLabel = UILabel()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        currentValueLabel.frame = .zero
        currentValueLabel.backgroundColor = .red
        currentValueLabel.textColor = .white
        currentValueLabel.font = UIFont.boldSystemFont(ofSize: 13)
        currentValueLabel.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        currentValueLabel.alpha = 0
        addSubview(currentValueLabel)
        
        layer.cornerRadius = frame.height / 2
        
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func trackRect(forBounds bounds: CGRect) -> CGRect {
        let customBounds = CGRect(origin: bounds.origin, size: CGSize(width: bounds.width, height: 15))
        super.trackRect(forBounds: customBounds)
        return customBounds
    }
    
    private func getThumbViewRect() -> CGRect {
        return self.thumbRect(forBounds: self.bounds, trackRect: self.trackRect(forBounds: self.bounds), value: self.value)
    }
    
    private func updateValueLabelValueAndPosition() {
        let thumbRect = getThumbViewRect()
        currentValueLabel.frame = thumbRect
        currentValueLabel.text = String(format: "%.2f", self.value)
        currentValueLabel.center = CGPoint(x: thumbRect.midX, y: thumbRect.minY - self.currentValueLabel.frame.height)
    }
    
    private func animateValueLabel(fading: Bool = true) {
        
        let thumbRect = getThumbViewRect()
        
        UIView.animate(withDuration: 0.3) {
            self.currentValueLabel.alpha = fading ? 1.0 : 0.0
            self.currentValueLabel.center.y = fading ? thumbRect.minY - self.currentValueLabel.frame.height : thumbRect.minY
        }
    }
    
    override func beginTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
        let touchPoint = touch.location(in: self)
        
        if getThumbViewRect().contains(touchPoint) {
            animateValueLabel()
        }
        
        return super.beginTracking(touch, with: event)
    }
    
    override func continueTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
        updateValueLabelValueAndPosition()
        return super.continueTracking(touch, with: event)
    }
    
    override func endTracking(_ touch: UITouch?, with event: UIEvent?) {
        animateValueLabel(fading: false)
        return super.endTracking(touch, with: event)
    }
    
    override func cancelTracking(with event: UIEvent?) {
        return super.cancelTracking(with: event)
    }

}