iOS Badge like UILabel glitch

please help me to make a simple badge like UILabel.

My code is:

let badgeLabel = UILabel(frame: CGRectMake(0, 0, 25, 25))
badgeLabel.backgroundColor = UIColor.clearColor()
badgeLabel.layer.backgroundColor = UIColor.redColor().CGColor
badgeLabel.layer.cornerRadius = 25/2
badgeLabel.layer.borderWidth = 3.0
badgeLabel.layer.borderColor = UIColor.whiteColor().CGColor

And in result I have a UILabel with tiny red stroke on white border: