Simple spark graph NSView example written in Swift. Open with Xcode for live preview and coding.

SparkGraph.playground

import Cocoa
import XCPlayground

@IBDesignable
class SparkGraph: NSView {
    
    // Background Colour
    @IBInspectable var backgroundColor:NSColor?
    
    // Border
    @IBInspectable var borderColor:NSColor?
    @IBInspectable var borderLineWidth:CGFloat?
    
    // Sparkline
    @IBInspectable var lineWidth:CGFloat?
    @IBInspectable var maxValues:Int {
    didSet {
        self.values = Array(self.values[0..self.maxValues])
    }
    }
    @IBInspectable var yMax:Int?
    
    var values: Int[] {
    didSet {
        setNeedsDisplayInRect(self.frame)
    }
    }
    
    init(frame: NSRect, values:Int[]) {
        self.values = values
        self.backgroundColor = nil
        self.borderColor = NSColor.grayColor()
        self.borderLineWidth = 1.0
        self.lineWidth = 1.0
        self.maxValues = 60
        self.yMax = nil
        super.init(frame: frame)
    }
    
    override func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)
        
        // Background
        if (self.backgroundColor) {
            self.backgroundColor!.setFill()
            NSRectFill(self.bounds)
        }
        
        // Border
        if (self.borderLineWidth! > 0 && self.borderColor) {
            let frameRect = self.bounds
            let newRect = NSMakeRect(frame.origin.x + 1, frame.origin.y + 1, frame.size.width - 1, frame.size.height - 1)
            var borderPath = NSBezierPath(rect:newRect)
            
            borderPath.lineWidth = self.borderLineWidth!
            self.borderColor!.setStroke()
            borderPath.stroke()
        }
        
        // Check for at least two values
        if (self.values.count < 2) {
            return
        }
        
        // Graph
        let innerRect = NSMakeRect(self.frame.origin.x, self.frame.origin.y, self.frame.width - (1.5 * self.borderLineWidth!), self.frame.height - ( 1.5 * self.borderLineWidth!))
        
        // Calculate maximum Y value (or use given)
        var yMax:Int? = nil
        if (self.yMax) {
            yMax = self.yMax
        } else {
            yMax = (self.values as AnyObject).valueForKeyPath("@max.self") as? Int
        }
        
        // Allow for border offset
        let xOffset = (self.borderLineWidth!/2)
        let yOffset = (self.borderLineWidth!/2)
        
        // Scale data points to frame
        let yRatio = Double(innerRect.size.height) / Double(yMax!);
        let xRatio = Double(innerRect.size.width) / (Double(values.count) - 1);
        
        // Create sparkline path
        var sparkline = NSBezierPath()
        sparkline.lineWidth = self.lineWidth!
        
        // Add data points to path
        for var i = 0; i < self.values.count; i++ {
            
            let x = (Double(i) * xRatio) + xOffset
            let y = (Double(values[i] as NSNumber) * yRatio) + yOffset
            
            let point = CGPointMake(x, y);
            
            if i == 0 { // starting point
                sparkline.moveToPoint(point)
            } else {
                sparkline.lineToPoint(point)
            }
        }
        
        // Draw sparkline
        NSColor.redColor().setStroke()
        sparkline.stroke()
    }
    
    func addValue(newValue:Int) {
        if self.values.count >= self.maxValues {
            self.values.removeAtIndex(0)
        }
        self.values.append(newValue)
    }
    
    func addValues(values:Int[]) {
        for value in values {
            self.addValue(value)
        }
    }
    
    func addValues(values:Int...) {
        self.addValues(values)
    }
}

var frame = NSRect(x: 0, y: 0, width: 1024, height: 128)
var values = [500, 200, 500, 600, 50, 80, 700, 900, 1000, 1000]

var s = SparkGraph(frame: frame, values: values)
s.backgroundColor = NSColor.whiteColor()
s.borderColor = NSColor.grayColor()
s.borderLineWidth = 1.0
s.lineWidth = 5.0
//s.yMax = 500
//s.maxValues = 3
//s.addValue(230)
//s.addValues(400,300,200,100,0)
//s.addValues(8,5,3,4,5,6,7,8,9,100)

XCPShowView("Spark Graph", s)