Progress View

ProgressView.swift

//
//  ProgressView.swift
//  ProgressView
//
//  Created by Daniel Cardona on 4/26/18.
//  Copyright © 2018 Daniel Cardona. All rights reserved.
//

import UIKit

class ProgressView: UIView {

    var progress : Float = 0 {
        didSet {
           displayProgress(progress)
        }
    }
    
    private var progressView : UIView!

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.setupView()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.setupView()
    }
    
    private func displayProgress(_ progress: Float) {
        let p = CGFloat(ProgressView.constrained(progress, max: 1, min: 0))
        let transform = CGAffineTransform(scaleX: p, y: 1.0)
        let newSize = self.frame.size.applying(transform)
        let offset = frame.size.width - newSize.width
        let newOrigin = CGPoint(x: offset , y: 0)
        progressView.frame = CGRect(origin: newOrigin, size: newSize)
        refreshViews()
    }
    

    func setupView() {
        progressView = UIView(frame: self.bounds)
        self.addSubview(progressView)
        progressView.backgroundColor = .green
        displayProgress(progress)
    }
    
    func refreshViews() {
        setNeedsDisplay()
        progressView.setNeedsDisplay()
    }
    
    // MARK: Helpers
    private static func constrained(_ scalar: Float, max: Float, min: Float)  -> Float {
        if scalar > max {
            return max
        }
        
        if scalar < min {
            return min
        }
        return scalar
    }
    

}