ArrayView.swift

import UIKit
class ArrayView : UIView {
    var data: Array<Int> = []
    var views: Array<UIView> = []
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    init() {
        super.init(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        self.backgroundColor = #colorLiteral(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0)
    }
    
    func setData(newData: [Int]) {
        data = newData
        updateViews()
        //setNeedsDisplay()
    }
    
    func updateViews() {
        // Iterate over data member, setting 
        if self.views.count != self.data.count {
            self.generateViews()
        }
        else {
            for (index, value) in self.data.enumerated() {
                self.views[index].frame = rectForBar(ofValue: value, atIndex: index)
            }
        }
    }
    
    func scalingFactor() -> CGFloat {
        guard let largestValue = data.max() else {
            return 1.0
        }
        let height = self.frame.size.height
        return 1.0 / (CGFloat(largestValue) / (height * 0.95))
    }
    
    func scaledBarHeight(value:Int, scalingFactor:CGFloat) -> CGFloat {
        return CGFloat(value) * scalingFactor
    }
    
    func scaledBarHeight(forValue value: Int) -> CGFloat{
        return CGFloat(value) * scalingFactor()
    }
    
    func barWidthForBarCount(_ barCount:Int) -> CGFloat {
        let width = self.frame.size.width
        return width / CGFloat(barCount)
    }
    
    func rectForBar(ofValue value: Int, atIndex index: Int) -> CGRect {
        let barWidth = barWidthForBarCount(self.data.count)
        print(barWidth)
        let scalingfactor = scalingFactor()
        let xOrigin = CGFloat(index) * barWidth
        let barHeight = scaledBarHeight(forValue: value)
        let yOrigin = self.frame.size.height - barHeight
        return CGRect(x: xOrigin, y: yOrigin, width: barWidth, height: barHeight)
    }
    
    func generateViews() {
        for (index, value) in self.data.enumerated() {
            let rect = rectForBar(ofValue: value, atIndex: index)
            let view = UIView(frame: rect)
            view.backgroundColor = #colorLiteral(red: 0.968627452850342, green: 0.780392169952393, blue: 0.345098048448563, alpha: 1.0)
            view.layer.borderWidth = 1
            view.layer.borderColor = UIColor.red.cgColor
            addSubview(view)
            views.append(view)
        }
    }
    
}

func randomArray() -> [Int] {
    var a = [Int]()
    for i in 0..<10 {
        let v = Int(arc4random_uniform(1000))
        a.append(v)
    }
    return a
}

import PlaygroundSupport
let barView = ArrayView()

PlaygroundPage.current.liveView = barView
for _ in 0 ... 20 {
    if barView != nil {
        barView.setData(newData: randomArray())
    }
    else {
        fatalError("BarView disappeared")
    }
    RunLoop.current.run(until: Date(timeIntervalSinceNow: 2.0))
}