RadioBox.swift

class RadioBox: UIButton {
  
  var borderColor: UIColor = UIColor.lightGrayColor()
  var innerColor: UIColor = UIColor.linkTextColor()
  var borderWidthPercent: Int = 40 {
    didSet {
      borderWidthPercent = max(min(borderWidthPercent, 90), 10)
    }
  }
  
  override func drawRect(rect: CGRect) {
    super.drawRect(rect)
    
    let lineWidth:CGFloat = (rect.size.width / 2) * CGFloat(borderWidthPercent) / 100
    
    //
    // Draw border of radiobox
    //
    let circleBorder = UIBezierPath(ovalInRect: CGRectInset(rect, lineWidth/2, lineWidth/2))
    circleBorder.lineWidth = lineWidth
    borderColor.setStroke()
    circleBorder.stroke()
    
    //
    // Draw inner circle if state is selected
    //
    if selected == true {
      let innerCircle = UIBezierPath(ovalInRect: CGRectInset(rect, lineWidth, lineWidth))
      innerColor.setFill()
      innerCircle.fill()
    }
  }
}