Swift: Translation and Rotation of CGContext (iOS/Xcode)

gistfile1.txt

// This code accompanies the following post: http://sketchytech.blogspot.co.uk/2014/11/swift-translating-and-rotating.html

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let newView = View(frame: CGRect(x: 0, y: 0, width: CGRectGetWidth(self.view.frame), height: CGRectGetHeight(self.view.frame)))
        
        self.view.addSubview(newView)

    }

}

class View:UIView {
    override func drawRect(rect:CGRect)
        
    {
        // obtain context
        let ctx = UIGraphicsGetCurrentContext()
        
        // Decide on radius
        let rad = CGRectGetWidth(rect)/3.5
        // End angle will be 2*pi for any circle that begins at 0
        let endAngle = CGFloat(2*M_PI)
        
        // We could use CGContextAddEllipseInRect to draw a circle instead
        CGContextAddArc(ctx, CGRectGetMidX(rect), CGRectGetMidY(rect), rad, 0, endAngle, 1)
        // set stroke color
        CGContextSetStrokeColorWithColor(ctx,UIColor.whiteColor().CGColor)
        // Set line width
        CGContextSetLineWidth(ctx, 4.0)
        CGContextStrokePath(ctx)
        
        // save current state of context
        CGContextSaveGState(ctx)
        
        CGContextTranslateCTM(ctx, CGRectGetMidX(rect), CGRectGetMidY(rect))
        // rotation supplied in radians
        CGContextRotateCTM(ctx, CGFloat(M_PI*45/180))
        
        
        // create a mutable path
        let path = CGPathCreateMutable()
        // move to the starting point of the path
        CGPathMoveToPoint(path, nil, 0, 0)
        // add a line the length of the radius to path
        CGPathAddLineToPoint(path, nil, rad, 0)
        // add the path to the (translated and rotated) context
        CGContextAddPath(ctx, path)
        // set line width
        CGContextSetLineWidth(ctx, 4)
        // set line color
        CGContextSetStrokeColorWithColor(ctx,UIColor.whiteColor().CGColor)
        // stroke path
        CGContextStrokePath(ctx)
        
        // restore original state
        CGContextRestoreGState(ctx)
        
        
    }
}