UILabel not respecting truncate

This is puzzling me for a while. This is my code:

 let label:UILabel = UILabel(frame: CGRectMake(0, 0, obTextRect.width, obTextRect.height))
            label.text = stText
            label.backgroundColor = UIColor.redColor()
            label.textAlignment = NSTextAlignment.Center
            label.numberOfLines = 0
            label.lineBreakMode = NSLineBreakMode.ByTruncatingTail
            label.font = obDrawItem.m_obFont
            label.adjustsFontSizeToFitWidth = true
            label.minimumScaleFactor = 0.1
            label.layer.drawInContext(obContext)


            CGContextRestoreGState(obContext)

and this is the result I am getting...

The word proceeding does not "auto shrink" to fit the width. Also if I add a line break (n) then it works ok. Any ideas???