IndexCard.swift

//: Playground - noun: a place where people can play

import UIKit
import PlaygroundSupport

class IndexCardImageView: UIImageView {
    let topSpacing: CGFloat = 80.0
    
    var lineColor = UIColor.clear
    var lineWidth: CGFloat = 1.0
    var topLineColor = UIColor.clear
    var topLineWidth: CGFloat = 2.0
    
    init(frame: CGRect,
         lineSpacing: CGFloat = 35.0,
         withLines: Bool = true,
         backgroundColor: UIColor = UIColor(red: 0.9999, green: 0.9956, blue: 0.9749, alpha: 1.0),
         lineColor: UIColor = UIColor(red: 0.3964, green: 0.6393, blue: 0.9988, alpha: 0.5),
         topLineColor:UIColor = UIColor(red: 0.8338, green: 0.3722, blue: 0.3937, alpha: 0.5)) {
    
        super.init(frame: frame)
        
        self.backgroundColor = backgroundColor
        self.topLineColor = topLineColor
        self.lineColor = lineColor

        self.image = self.drawIndexCard(frame, lineSpacing: lineSpacing, withLines: withLines)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func drawIndexCard(_ rect: CGRect, lineSpacing: CGFloat = 24.0, withLines: Bool = true) -> UIImage? {
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()!
        
        // top red line
        context.beginPath()
        context.setStrokeColor(topLineColor.cgColor)
        context.setLineWidth(topLineWidth)
        context.move(to: CGPoint(x: 0.0, y: topSpacing))
        context.addLine(to: CGPoint(x: rect.width, y: topSpacing))
        context.strokePath()
        
        // add blue lines if we want them
        if withLines {
            let deltaY: CGFloat = lineSpacing;
            let numberOfLines: Int = Int((rect.height - topSpacing) / deltaY)
            context.beginPath()
            context.setStrokeColor(lineColor.cgColor)
            context.setLineWidth(lineWidth)
            for i in 1...numberOfLines {
                let Y = CGFloat(i) * deltaY;
                context.move(to: CGPoint(x: 0.0, y: topSpacing + Y))
                context.addLine(to: CGPoint(x: rect.width, y: topSpacing + Y))
            }
            context.strokePath()
        }
        
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        return image
    }
}

let windowFrame = CGRect(x: 0.0, y: 0.0, width: 375, height: 667)
let cardImageView = IndexCardImageView(frame: windowFrame)

PlaygroundPage.current.liveView = cardImageView
PlaygroundPage.current.needsIndefiniteExecution