Calculate height of multi-line UILabel

    func heightForLabel(#fontSize: CGFloat, labelWidth: CGFloat) -> CGFloat {
        let label:UILabel = UILabel(frame: CGRectMake(0, 0, labelWidth, CGFloat.max))
        label.numberOfLines = 0
        label.lineBreakMode = NSLineBreakMode.ByWordWrapping
        label.font = UIFont(name: "HelveticaNeue", size: fontSize)
        label.text = self
        label.sizeToFit()
        return label.frame.height
    }
To make a custom UILabel with correct height automatically:
class YourLabel: UILabel {  
    required init(coder decoder: NSCoder) {
        super.init(coder: decoder)
    }

    init(text: String, fontSize: CGFloat, frame: CGRect){
        super.init(frame: CGRectMake(frame.origin.x, frame.origin.y, frame.width, text.heightForLabel(fontSize: fontSize, labelWidth: frame.width)))
        self.numberOfLines = 0
        self.lineBreakMode = NSLineBreakMode.ByWordWrapping
        self.font = UIFont(name: "HelveticaNeue", size: fontSize)
        self.text = text
        self.sizeToFit()
    }
}
Then you will be able to use it like:
YourLabel(text: "Label Name", fontSize: 12.0, frame: CGRectMake(0, 0, 100, 0))  
// The height value in the frame won't be used and can be any value