CGContextRef isn't working with @IBDesignable (Error:The agent Crashed)

I am creating a UIButton subclass to add some drawing . It is working fine in code . It is giving following error when i am trying via @IBdesignable .

1. error: IB Designables: Failed to update auto layout status: The agent crashed

2. error: IB Designables: Failed to render instance of DashboardHeaderView: The agent crashed

Following is code sample

let context:CGContextRef = UIGraphicsGetCurrentContext()!
UIGraphicsPushContext(context)
UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0);

var path:UIBezierPath!
let pathRect:CGRect = CGRectMake(strokeWidth / 2, strokeWidth / 2, pathSize - iconStrokeWidth, pathSize - iconStrokeWidth);
path = UIBezierPath(rect: pathRect )
iconColor.setStroke()
iconPath.lineWidth = iconStrokeWidth;
iconPath.stroke()
CGContextAddPath(context, iconPath.CGPath);

let image:UIImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsPopContext();
UIGraphicsEndImageContext();

Agent crashing error is at

let context:CGContextRef = UIGraphicsGetCurrentContext()! 

I overirde init + drawRect + initilizeButtonDrawings but got nothing positive

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)!
    self.initilizeButtonDrawings()
}

override init(frame: CGRect) {
    super.init(frame: frame)
    self.initilizeButtonDrawings()
}

override func drawRect(rect:CGRect) {
    super.drawRect(rect)
    self.initilizeButtonDrawings()
}
override func prepareForInterfaceBuilder () {
    self.initilizeButtonDrawings()
}

All this is working fine with Objective C but crashing in swift

I solved this via following update...

let rect:CGRect = CGRectMake(0, 0, iconSize, iconSize)

UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0);
let context  = UIGraphicsGetCurrentContext()
 // draw icon

var iconPath:UIBezierPath!
let iconRect:CGRect = CGRectMake(iconStrokeWidth / 2, iconStrokeWidth / 2, iconSize - iconStrokeWidth, iconSize - iconStrokeWidth);
if self.iconSquare {
    iconPath = UIBezierPath(rect:iconRect )
} else {
    iconPath = UIBezierPath(ovalInRect:iconRect)
}
iconColor.setStroke()
iconPath.lineWidth = iconStrokeWidth;
iconPath.stroke()
CGContextAddPath(context, iconPath.CGPath);
let image:UIImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();